As the main component of the train body structure, the truss-cored flat panel is situated close to the wheel-track noise source and has a large area for noise radiation, and its acoustic performance directly influences the riding comfort of trains. This paper first establishes the wavenumber finite-element model and a sound-insulation prediction model for an aluminum truss-cored train floor using wavenumber finite elements and boundary integral equations. The wavenumber, transmission loss, and eigenvectors of the structure are calculated. The dispersion characteristics, sound-insulation performance and cross-sectional wave-modes of elastic waves are studied. The calculated results are compared with the prediction given in the references to verify the proposed model. Furthermore, this paper investigates the effects of the core layer's topological geometry of the extruded panel on the sound-insulation characteristics of aluminum extruded panels. The results show that varying the topological configuration of the core layer significantly changes the variation pattern of dispersion curves of elastic waves, which affects the sound-insulation properties of aluminum extruded panels. By comparing the topologies of classic extruded structures, it is found that the ‘herringbone’ ribbed plate structure has a relatively higher sound-insulation level and lower mass. This study can provide a reference for designing quiet and lightweight extruded panels.

The combined seismic isolation bearing is composed of a sliding friction bearing and an elastomeric bearing. The bearing system offers a substantial vertical support capacity, various post-yield stiffness choices, and the ability to separate the bridge’s vertical support system from the horizontal support system. To investigate the seismic performance of the combined seismic isolation bearing system, by way of example of a continuous beam bridge with each continuous unit of (4 × 40) m spans, the OpenSees software was used to model with the conventional spherical steel bearing, full sliding friction bearing and combined seismic isolation bearing support systems to obtain the longitudinal seismic response of the bridges, respectively. The influence of seismic parameters such as sliding friction coefficient and shear stiffness on the seismic performance of the combined seismic isolation bearing was discussed. The results demonstrated that the combined seismic isolation bearing exhibits excellent seismic performance and self-centering ability. The seismic performance of the combined isolation bearing will be affected by the sliding friction coefficient and shear stiffness. By selecting appropriate seismic parameters, the maximum displacement demand of bearings, the residual displacement of bearings, and the seismic response of the piers can be effectively controlled.

As the thermonuclear fuel container in inertial confinement fusion (ICF), the surface quality of the target capsule directly affects the success of ICF experiments. Therefore, it is crucial to inspect the morphology of ICF microspheres before fabrication. To address the issue of secondary damage to the surface of ICF microspheres during manipulation by current detection equipment, a bulk acoustic wave-driven microsphere manipulation device is proposed. This device excites an out-of-plane bending vibration mode in a vibrator composed of a piezoelectric ceramic and a metal substrate, creating an acoustic field within the liquid. The ICF microspheres are then driven by non-contact acoustic radiation forces, enabling non-destructive manipulation during ICF microsphere inspection. To analyze the relationship between the vibration of the manipulation device and the generated acoustic field, we developed an electromechanical coupling dynamics model of the vibrator using the transfer matrix method. This model comprehensively considers factors such as the size, material, boundary conditions, arrangement of piezoelectric ceramic sheets, excitation voltage, and additional load from water of the vibrator. Using this model, we calculated the vibration modes of a non-resonant traveling wave and two resonant standing waves, along with three corresponding acoustic fields. Based on calculation results, we fabricated and assembled the prototype. Vibration characteristics and manipulation performance of the prototype were studied through experiments. The results indicate a good agreement between theoretical calculations and experimental tests regarding the vibration characteristics of the acoustic manipulation device, validating the correctness of the established dynamics model. Both non-resonant traveling waves and resonant standing waves can effectively manipulate ICF microspheres, with the resonant standing wave achieving faster microsphere movement. This confirms the feasibility and effectiveness of the proposed acoustic manipulation method. Furthermore, based on the modal switching measurement and control method, the device can classify ICF microspheres by diameter without the need for a microscope.

To upgrade the level of rural housing to meet the increasing demand for comfort, safety, environmental protection and energy saving, a light frame structure system housing was proposed and designed. The light frame structure system takes a steel frame as the main structural body and ALC wall panel as the filling wall. A full-scale shaking table test has been carried out to verify its seismic performance and to study the seismic behavior and seismic response law of the light frame structure system under earthquake action on beam-column joints, wall-slab joints, and the building structure. The test results show that the wall panel has not fallen off, the joint connection is intact, and the structure has not collapsed. With the increase of input seismic intensity, both the acceleration amplification factor and relative displacement increase, while the natural frequency of the structure decreases gradually. Throughout the test, the main structural members remain elastic, and the inter-story displacement angle of the structure under a fortification earthquake of 6-degree is less than 1/250. Under the action of rare earthquakes of 7th intensity and 8th intensity, the inter-story displacement angle of the structure exceeds 1/250, but the structural deformation can be reduced by tensioning reinforcement support. The light frame structure system exhibited excellent seismic performance and can be used to improve the level of rural housing in the 6th intensity seismic fortification area. For seismic fortification areas above 6th intensity, the seismic performance can be enhanced by increasing the tension of tie bars.

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.

In order to accurately identify cable force in complex boundary conditions，a new method of cable force identification using machine vision and generalized regression neural network（GRNN）is proposed. Machine vision technologies，such as the phase-based motion amplification algorithm and sub-pixel edge detection algorithm，are used to extract the vibration displacement time history data and identify the frequency through the cable vibration video to realize multi-point non-contact synchronous measurement of cable vibration deformation. A sample dataset is generated using the finite difference method. The smoothing factor of GRNN is obtained by the sparrow search algorithm（SSA），and a SSA-GRNN cable force prediction model is constructed，establishing the correspondence between frequencies and cable force under complex boundary conditions. The obtained frequency information is input into the model for cable force recognition. Taking a single cable as an example，the numerical simulation of the cable in complex boundary conditions and the cable test under artificial excitation condition are carried out. The results show that the cable force identification using machine vision and GRNN can accurately identify frequencies through vibration video，and improve the recognition accuracy of the cable force in complex boundary conditions.

To enhance the accuracy of instantaneous frequency（IF）identification for non-stationary response signals of time-varying structures，a locally optimized multi-synchrosqueezing-short time fractional Fourier transform（LOMS-STFRFT）algorithm is proposed in this paper. Firstly，the local rotation parameters of the short time fractional Fourier transform（STFRFT）are optimally selected in this method. Subsequently，the time-frequency coefficient matrix projected to the fractional domain is obtained through STFRFT. After that，IF estimation and multiple iterations are performed on the time-frequency coefficient matrix. The time-frequency coefficient matrix is reassigned by the multi-synchrosqueezing operator，and IF curves are then extracted via the local mode maxima method. The accuracy of the proposed method is validated through a numerical example of a multi-component signal and a linearly time-varying cable test. The results demonstrate that the proposed LOMS-STFRFT algorithm behaves better than traditional multi-synchrosqueezing transform on IF identification of non-stationary signals from time-varying structures.

Inerters and negative stiffness devices can improve the energy dissipation performance of vibration absorbers. An increasing number of applications of them in novel high-performance vibration suppression have been witnessed. In this paper，analytical parametric optimization analyses on the tuned inerter mass systems with negative stiffness（NS-TIMS）are performed. A unified model of governing equations and transfer functions for NS-TIMS under different installation locations，application scenarios（such as inter-layer vibration absorption，and base isolation）and excitation types is established. Based on the fixed-point theory，the optimal parameters of NS-TIMS considering both H_∞ and H₂ norms are analytically derived. Considering typical application conditions，the analytical formulas are further analyzed and simplified. Consequently，the design formulas for the optimal parameters of NS-TIMS based on the“equivalent inertial mass ratio” are proposed. The application scopes of the design formula are discussed. Through numerical cases on the practical examples of wind-induced vibration control and seismic base isolation，the effectiveness of the design formulas considering the actual structural damping ratio and spectral characteristics of stochastic excitations is verified. It is also revealed that NS-TIMSs have superior performances in both high flexible structure vibration absorption and auxiliary base vibration isolation.

A nonlinear enhanced bellows-type hydraulic inerter-based antiresonance vibration isolator is proposed for low-frequency line spectra vibration isolation. The nonlinear dynamic model of the enhanced system and the quasi-static model with bistable negative stiffness are established. The influence of parameters such as geometric dimensions and elastic coefficients on the nonlinear stiffness characteristics of the system is studied. It is found that the structure with negative stiffness enhancement only regulates the extent of nonlinear stiffness without changing the load-bearing capacity or static deformation. Subsequently，an estimation analysis of vibration isolation performance is conducted. The vibration transmissibility of the degraded linear system under force excitation is studied，and the effects of non-dimensional parameters，including the inertial mass ratio，effective area ratio，and damping ratio，on the transmissibility characteristics are analyzed. The dynamic response is solved by using the averaging method，and the analytical solution steps for the transmissibility of the nonlinear enhanced system are given based on the equivalent linearized stiffness. The analytical results are validated by comparing them with numerical simulation results，showing small relative errors，and thus can be used for design purposes. A comparative study is conducted on the transmissibility characteristics of the nonlinear negative stiffness enhanced hydraulic inerter-based vibration isolation system. The results indicate that the introduction of a bi-stable negative stiffness can lower the resonance and anti-resonance frequencies of the isolation system. By designing appropriate inertial mass parameters，it is possible to achieve superior wideband isolation effectiveness in the low-frequency range.