The present study aims to improve the aerodynamic stability of a single-axis PV tracker. The effects of turbulence intensity, natural frequency and damping ratio on the aerodynamic stability of the single-axis PV tracker are studied by a sectional model wind tunnel test to reveal the sensitivity of these parameters. The results show unstable torsional vibration of the single-axis PV tracker system in a large tilt angle range with strong aerodynamic coupling and self-excited characteristics. The critical wind speed for the unstable vibration is low. The critical wind speed is high at 0° tilt angle (PV module is horizontal). The increase of turbulence intensity leads to the increase of the unstable vibration tilt angle range, which is not good for the aerodynamic stability. Increasing the damping ratio has an inconsiderable effect on increasing the critical wind speed at small tilt angles (0° and 5°). However, it works well when the tilt angle is larger than 15°. With the increase of natural frequency, the critical wind speed is significantly increased at all tilt angles.

Aiming at the problem of secondary impact caused by mismatching parameters of traditional isolation system with displacement restrictor, firstly, a mechanical model of the quasi-zero stiffness (MMPDQZS) isolation system was established by using the opposed disc spring as the negative stiffness component and the repulsive permanent magnets was used to adjust the nonlinear positive stiffness. The static characteristics of the system were analyzed. Then, the mathematical model of MMPDQZS isolation system was established. The influence law of different damping parameters on the impact isolation performance of MMPDQZS isolation system was analyzed. The impact characteristics were compared and analyzed through simulation and experimental study for without and with equivalent linear displacement restrictors and MMPDQZS limiters. The results show that for any initial clearance, there is an optimal viscous damping ratio that minimizes the system’s buffer coefficient. Smaller initial clearances generally lead to better impact isolation effects. Considering different initial clearance, the damping ratio of power-law fluid damping is 0.02, the velocity correlation index obtains the optimal buffer coefficient within the interval [2.2, 2.3], and the optimal initial clearance is when the clearance is equal to 4 mm. For any initial clearance, the buffer coefficient is proportional to coulomb damping, and smaller initial clearances result in better buffering performance. Compared with the equivalent linear limit isolation system, MMPDQZS limit isolation system can not only effectively limit the relative displacement, but also greatly reduce the buffer coefficient of the system and improve its impact resistance.

The acoustic black hole (ABH) effect, which decelerates the propagation of elastic waves and suppresses boundary reflections, presents a novel mechanism for vibration energy harvesting. A dual-ABH piezoelectric beam energy harvester has been designed for application in railway track systems. A semi-analytical electromechanical coupling model was developed using the energy functional variational principle and Gaussian expansion method. Validation was conducted through finite element simulations. Under train-induced loading, energy harvesting behavior was investigated with respect to ABH geometric parameters and terminal mass. Four principal energy harvesting bands were identified within the 0~1500 Hz range, yielding a peak output voltage of 4.83 V and a maximum efficiency of 2.23%. Optimal energy conversion was achieved when the piezoelectric patch length equaled half the bending wave wavelength of the host structure. Efficiency was further improved by strengthening the ABH effect or through appropriate tuning of the terminal mass.

A structural system for energy dissipation and shock absorption with displacement amplification damping walls across multiple stories is presented. According to structural characteristics of the cable-bracing displacement amplification damping wall, the deformation and force characteristics of the device were analyzed, and presented theoretical formulations for the cable-type damping wall system’s damping force and energy dissipation. The simplified numerical model was established, the parameters that affect the structural performance indicators were analyzed in detail, the fixed-point theory was used to design the optimal parameters of the cable-type damping system, and the energy-dissipating deformation magnification equation was derived to quantify the degree of damping efficiency. A 30-story concrete frame core tube was analyzed for the seismic time-history analysis, though the vibration absorption efficiency of the three damping wall layout schemes of displacement amplification damping wall installed in single story and cable-bracing displacement amplification damping wall system installed in multi-story were compared, it is found that the cable-bracing displacement amplification damping wall system installed in multi-story has a better shock-absorption effect.

To realize the resilience of structure under earthquake and solve the problem of large residual deformation of energy dissipation dampers, a prefabricated self-centering energy dissipation brace assembled with U-shaped steel plates and pre-compressive disc springs (U-SCEB) has been developed. This innovative brace comprises a pre-compressive disc spring self-centering system and a U-shaped steel plate energy dissipation system, assembled in parallel. Compared to previous self-centering energy dissipation braces with combined disc springs, the U-SCEB has better deformation capacity and can be fully assembled on-site, facilitating the replacement of damaged U-plates after an earthquake. The configuration and working principle of the U-SCEB were described, and its restoring force model was established. The self-centering capability of the combined disc springs and the energy dissipation capability of the U-shaped steel plates were investigated by the quasi-static cyclic loading test, and the hysteretic behavior of the U-SCEB was further studied by the quasi-static loading test. Finally, the finite element model of the brace was established, and the influence of different design parameters on the hysteretic performance of the U-SCEB was analyzed. The results show that the configuration of the brace is simple, and the self-centering principle is clear. The brace can be assembled on-site, and the components are replaceable. The restoring force model of the brace presents a typical flag shape. Under the quasi-static cyclic loading, damage to the brace is mainly manifested as plastic damage at the connection between the flat and bent sections of the U-shaped steel plate, and the hysteresis curve exhibits stable energy dissipation, excellent self-centering ability, and significant deformation capacity. To ensure the excellent self-centering capacity of the brace, the pre-compressive force of the disc springs should be larger than or equal to the peak strength of the U-shaped steel plates.

At present, the research of asphalt concrete core dam under near-fault ground motion is mostly carried out under the condition of single SV and P wave oblique incidence. In fact, the assumption of single wave oblique incidence is not comprehensive, and the near-fault ground motion should be considered as the case of combined P wave and SV wave oblique incidence. In this paper, the oblique incidence time history of SV wave and P wave in the site was determined based on ground motion inversion, and the deformation and damage of the core wall dam were obtained under the oblique incidence of SV and P wave combination near the fault, and the change law of the damage of the dam body with the horizontal and vertical ground motion intensity index was analyzed. The results show that the ultimate failure probability caused by the vertical near-fault ground motion index is obviously different from that caused by the horizontal direction. When the horizontal ground motion intensity indicators near the fault are selected as S_a(T₁)₁, S_v(T₁)₁, VSI₁ and S_d(T₁)₁, and the vertical ground motion intensity indicators are selected as PGA₂, S_a(T₁)₂, VSI₂ and S_d(T₁)₂, the predicted failure probability of the dam body is moderate. The combined damage analysis method of horizontal and vertical ground motion should be considered when analyzing the vulnerability of core wall dam under near-fault ground motion.

For cross domain diagnosis of the label spaces of source domain and target domain are partially overlapped，that is to say，both the target domain and the source domain contain the classes that the other does not have，a cross domain adaptive fusion diagnosis method based on weighted adversarial learning is proposed. As entropy can be used to reflect the characteristics of the shared known classes and unknown classes，two convolutional neural networks with the same structure are introduced to carry out entropy-based weighted adversarial training，which is aim to enhance the ability to identify the shared known classes by extracting the domain-invariant features，as well as the binary cross schemes of the source domain and target domain sample outputs are used to isolate the unknown classes. In addition，the fully connected layer hidden features of these two convolutional neural networks are taken as the input of two label transfer models，and the probability outputs of these three diagnostic models are fused by voting rule. The failure test bench data of mechanical transmission components under variable working conditions and the damage data of selfpriming centrifugal pump are used for analysis and verification，the experimental results show that the proposed cross domain adaptive fusion diagnosis method can distinguish the shared known classes and unknown classes in the target domain more accurately.

Based on the three-dimensional finite element slope dynamic analysis model which is validated through the test data of 1：7 indoor physical model for live tree stump，the attenuation characteristics of additional dynamic stress on live tree stump slopes，the stress response characteristics of taproot and lateral root of live tree stumps，and the influence of live tree stumps on slope stability are studied. The dynamic stability mechanism of live tree stump slope is explored. The research conclusion is as follows. The peak value of vertical dynamic soil pressure calculated by the three-dimensional finite element dynamic analysis model is close to the measured results of the indoor physical model. The method and calculation results of the three-dimensional finite element dynamic analysis model of the live tree stump slope established through Midas GTS NX are reliable. The peak value of additional dynamic stress on the slope is affected by the superposition effect of train axle load. The higher the train movement speed，the greater the peak value of vertical dynamic stress. The additional dynamic stress in the ballast layer is the largest，it rapidly decays and diffuses downwards showing a semicircular arc shape. Only small dynamic stresses are transmitted to the two rows of live trees on the upper slope. The degree to which the shear resistance of the taproot of live tree stumps varies at different positions，and the taproot at the foot of the slope is subjected to greater shear stress compared to the taproot at the shoulder of the slope. The taproot is similar to the anti-slide pile to exert its shear resistance ability. The side roots of live tree stumps growing inside the slope are similar to anchor rods，while the side roots growing outside the slope are similar to supports，and they form an anchor-support effect that synergizes with the main root to play a sliding resistance role. The existence of live tree stumps leads to a redistribution of stress in soil，and the shear stress concentration near the live tree stumps. The live tree stumps hinder the transmission of shear stress in soil，inhibit the connectivity of plastic zones，and improve slope stability. The degree of influence on the horizontal dynamic displacement of the slope is related to its distance to the location of the dynamic load，and the closer the distance，the greater the impact. The live tree stumps can reduce the horizontal dynamic displacement at various points on the slope，but the reduction at the foot of the slope is the greatest. The live tree stumps can significantly improve the stability of slopes under train power，and their slope safety factor can be increased by 15%~20%. The potential sliding surface of the live tree stump slope presents a circular arc shape，and the live tree stump moves the plastic zone towards the deep soil layer，thereby improving the stability of the slope. The research results can provide certain guidance for the application of live tree stumps in roadbed slopes.

An axisymmetric finite element-boundary element coupled computational method is proposed for the dynamics of cylindrical shells with endplates in water. Due to the periodic characteristics of the structure，the movement of the cylindrical shell and end plate can be determined by examining their meridional movement，and the meridians are discretized into several elements for further analysis. By using the energy method，the elemental matrices are obtained and assembled into the global matrices. Then the discrete schemes for structural motion with the finite element is established. Considering the axisymmetric characteristic of the fluid，an axisymmetric boundary element on the meridians is established and the calculation format for fluid-elastic forces on the finite elements is given. The fluid forces are then converted into an equivalent nodal force at the nodes and the effects of the fluid are evaluated by the added mass，damping，and stiffness matrices. By combining the structural motion and the schemes of fluid-elastic forces，an axisymmetric finite element-boundary element coupling method is developed to solve this fluid-structure coupling problem. The calculated results presented in this paper demonstrate good agreement with existing theoretical solutions and commercial analysis software，validating the accuracy of present method. Moreover，this method exhibits higher computational efficiency compared to commercial analysis software. It allows for direct determination of the mass and stiffness matrices of cylindrical shells in fluid，facilitating fast calculation of forced vibration. Based on this method，the wet frequencies and stability characteristics of complex cylindrical shells with end plates in axial flow are analyzed. The results show that the end plates will change the flow velocities on the cylindrical shell and make it more easily to instability.

The axle-box bearing is a key component of high-speed trains，and the wheel-rail excitation caused by complex braking conditions leads to extremely complex vibration and contact characteristics of axle-box bearings and it is unclear until now. Therefore，a rigid-flexible coupled dynamics model of a high-speed train considering braking systems and axle-box bearings is established. Moreover，the braking system，axle-box bearing and vehicle system are dynamically coupled via the nonlinear friction of the braking interface，wheel-rail interactions，nonlinear contact of the axle-box bearing and suspension systems. Further，the field tests are conducted to verify the effectiveness of the established model. Based on this，the vibrations，bearing internal force，and contact characteristics of axle-box bearings under different braking conditions are systematically studied. The results indicate that train braking increases the longitudinal force of the axle-box bearings on the first and second wheel-set，and enhances the longitudinal vibration. The vertical vibration of the axle-box is slightly influenced by braking. In addition，when the train brakes，the friction between disc and pad makes the pitch motion for bogie frame，causing changes in the primary suspension force on the first and second wheelset，resulting in a decrease in the vertical force of axle-box bearing on the first wheel-set，an increase in the vertical force of the axle-box bearing on the second wheel-set，and ultimately an increase in the maximum roller-raceway and contact stress of the axlebox bearing on the second wheel-set.