With the development of civil aircraft design technology, the focus of today's passenger aircraft design transits from structural safety to cabin comfort, of which the vibration comfort is a key factor. From the perspective of passenger vibration comfort, We carried out the vibration transfer path test of a certain type of passenger aircraft under three working conditions, namely, the cruising condition, the low-altitude flight condition, and the runway running condition. Based on the test data of these conditions, the Vibration Transfer Path models were built, and the key factors affecting the vibration comfort were studied. The following conclusions are drawn:Under the cruising and low-altitude flight condition, the cabin vibration response mainly comes from the coupling of engine rotor excitation and the structure at the fundamental frequency and the double frequency；under the runway running condition, the vibration response in the cabin comes from the coupling of the main landing gear excitation and the structure in the low frequency range（especially 50 Hz）. This test not only provides a basis for the vibration reduction and isolation design of passenger cabins, but also fills the gap of the vibration comfort test and verification platform for all passenger aircraft in China.

There are complex flow phenomena in the inlets of the air-breathing hypersonic vehicles, such as boundary layer transition, flow separation, and shock/boundary layer interference. Deep understanding and effective control of these complex flow phenomena are the key to realizing effective operation and performance improvement of hypersonic vehicles. The current research progress of shock/boundary layer flow control technology in supersonic inlets is first reviewed from two aspects:passive control and active control；their effectiveness and drawbacks are described. Meanwhile, with the development of hypersonic vehicle towards the direction of wide velocity domain, large airspace and high Mach number, the previous flow control technology based on active and passive control cannot meet the requirements of hypersonic vehicle follow-up control. As a result, the multi-field control methods represented by plasma have become the focus of supersonic inlets flow control. However, the existing experimental research methods are difficult to carry out detailed research on flow control mechanisms, and there are still many places worth exploring. In this paper, relevant suggestions are put forward for the next step of research in addition to summarizing.

Aiming at the demand for torsional capacity of high-power offshore wind power supporting structure, the full-range torsional mechanism of tapered concrete-filled double skin steel tubular（TCFDST）members was examined under the large hollow ratio, high taper degree, and out-of-code diameter-to-thickness（D/t）ratio. The characteristics of torque-angle curve could be divided into the elastic stage, elasticplastic, plastic strengthening stage, and failure stage. Influence of key parameters on ultimate bearing capacity and stiffness was revealed. The hollow ratio and strengths of steel and concrete were positively correlated with the ultimate torque and stiffness；D/t ratios of outer or inner tubes had negative relationship to it；the axial compression ratios had positive relationship within the limited value，and inversely，it was negatively correlative. A method based on laminated tube theory was proposed to calculate the torque-angle curves of TCFDST members. Subsequently，the hierarchical integration method was established and verified based on the Chinese code and relevant literature，for calculating the ultimate torsional capacity of concrete-filled double skin steel tubular members，and the difference of various methods in determining N-T curve was also analyzed. The research results in this paper can provide valuable reference for the application of TCFDST members with large hollow ratios，large taper degree，and out-of-code D/t ratios in wind power projects.

In this paper, the effects of doping elements（Re and Ru）content on the stability and occupancy orientation of a Ni-Al binary model nickel-based single-crystal superalloy are studied by using first-principles calculations. The results show that the total energy of the system decreases gradually with the increase of the content of Re and Ru elements, which suggests that the stability of the system is improved. The system using Ru to replace Ni has the lowest stability, while the stability of system is the best by using Re to replace Al. Therefore, Re and Ru are more inclined to replace Al, which is consistent with the previous experimental results. Meanwhile, compared to other contents of Re and Ru, when Re and Ru with the content of about 1.4% are used to replace Al, the substitution formation energy is the lowest. Furthermore, two different stacking fault modes are obtained by deleting a layer of atoms in the Ni-Al binary model. Research on these two stacking fault modes indicates that replacing Al with Re and Ru can improve the stability of the systems, and systems containing Re are more stable, which have lower substitution formation energy compared to replacing Al with Ru. However, for different stacking fault modes, when replacing Al with Re and Ru, the content of Re and Ru is different for the best of a stable system and the lowest of substitution formation energy and stacking fault energy. Replacing Al with Re results in a better stability in stacking fault systems, but the content of Re in the most stable system depends on the selected stacking fault mode.

In steel-concrete composite structures, due to the existence of certain interface slip and web shear deformation, the assumption of flat section is no longer applicable. In order to scientifically study the effects of shear deformation and interface slip on the deflection and interface slip of composite beams, this paper adopts Goodman's assumption and Timoshenko beam's double generalized displacement assumption, introduces the strain relationship of composite beams and element microsegment mechanical equilibrium, and derives the elastic bending differential equation of double inverted T-shaped steel-concrete composite beams considering shear deformation and interface slip. Then based on the equivalent spring model and the equivalent rod spring model, a theoretical calculation formula for the elastic shear stiffness of the embedded web connection is derived. By using the known deformation and constraint conditions of the composite beam, we obtain the analytical solution of deflection and slip of the simply supported composite beam under concentrated load in the span and verify it through the experimental results of four double inverted T-shaped steel-concrete composite beams with different parameters. The results show that the deflection and slip values obtained from theoretical calculations are in good agreement with the measured values, and the correctness of the theoretical calculation formula for the elastic shear stiffness of the embedded web connection is verified. In the deflection deformation of double inverted T-shaped composite beams, the deflection value caused by bending accounts for about 56% of the total deflection, the deflection value caused by interface slip accounts for about 36% of the total deflection, and the deflection value caused by shear deformation accounts for about 8% of the total deflection. This article comprehensively considers the effects of shear deformation and interface slip on the deflection and slip of composite beams, and makes a significant improvement compared to the model structure that does not consider shear deformation and interface slip.

To study the effect of double circular holes on the mechanical properties of rocks and the crack extension process, a uniaxial compression model for rock specimens containing double circular holes was constructed, and the correctness and rationality of the numerical model were verified based on the comparison of the macroscopic mechanical parameters obtained from experiments and simulations. In addition, the crack extension process of specimens containing double circular holes and the evolution of the stress field around the circular holes were analyzed. The results show that the numerical simulation results are in good agreement with the experimental results；the initial tensile crack first sprouts at the upper and lower ends of the circular hole, and with the increase of axial stress, structural weak zones are usually formed at the left and right sides of the hole wall. The sprouting direction of the initial tensile crack is in the axial load-ing direction, independent of the orientation angle α, but the damage pattern of the specimen is influenced by the orientation angle α. The initial tensile crack is generated in the tensile stress concentration area；the tensile stress concentration area at the upper and lower ends of the circular hole moves and dissipates accordingly with the expansion of the initial tensile crack. The compressive stress concentration area of the stress component σ_yy is located on the left and right sides of the circular hole, while a shielding area of compressive stress is formed at the upper and lower ends of the circular hole, and the smaller the distance from the vertical center line of the circular hole, the stronger the shielding effect and the weaker the compressive stress.

This paper develops a free vibration model of rectangular microplates including three material length scale parameters and two displacement field variables using the modified strain gradient theory and a refined higher-order shear deformation theory, and presented the related governing differential equations. The analytical vibration frequencies of a four-edge supported rectangular microplate were obtained via the Navier method. Combining the Gauss-Lobatto quadrature and differential quadrature rules, a four-node seventy-two-DOF differential quadrature finite element was constructed to solve the free vibration of rectangular microplates with general boundary conditions. Through typical numerical examples, the effectiveness of the present model was established, and the effects of boundary conditions, material length scale parameters, aspect ratio and length-thickness ratio on the vibration frequencies and mode shapes of rectangular microplates were revealed. The results indicate that the vibration frequencies and some mode shapes of rectangular microplates exhibit significant size effect, and its intensity is associated with the boundary conditions and geometric dimensions.

The anti-yaw vibration devices currently used in high-speed trains are hydraulic dampers, whose damping characteristics cannot be adjusted according to the changes in the vehicle's operating state and environmental conditions, resulting in poor ride quality and stability for the vehicle. A semi-active damper based on magnetorheological technology combined with intelligent control technology can solve this problem. In this paper, a three-coil magnetorheological damper has been developed with adjustable damping characteristics based on the technical specifications of the anti-yaw damper. The multi-physical field of the damper is simulated, and damping performance of the damper is tested under different excitation currents, amplitudes, frequencies, and coil combinations. The results show that the magnetic circuit design of the damper is reasonable and complies with the technical requirements for anti-yaw dampers, with a maximum output force of 46 kN and an adjustable dynamic coefficient of 28. In addition, an analysis is conducted on the magnetic field distribution at varying coil spacings. The findings indicate that a critical distance exists between the coils, and the critical distance of this damper is 0.69 times the width of the coil, beyond which the magnetic field distribution becomes non-uniform. The change in magnetic flux density at the effective damping channel will stop when a certain part of the magnetic circuit reaches saturation.

Against the characteristic of large deformation for reinforced concrete（RC）frame, RC frame-frame truss composite wall（FTCW）structure was proposed, and two reinforced concrete（RC）frameframe truss composite wall（FTCW）specimens with a scale of 1∶2 were implemented for cyclic loading test. The seismic performance of bearing capacity, ductility and stiffness degradation were analyzed by the test phenomenon, hysteresis curves, backbone curves and stiffness degradation curves. The simulation of cyclic loading test was conducted by ABAQUS software, and the results were compared with the test results. The influence of the amount of infill FTCW, rebar ratio of RC frame columns, axial compression ratio, concrete strength, embedded angle steel and the layout direction of FTCW were analyzed. The test behav-iors showed that a multistage energy consuming system that FTCW worked before RC frame and the internal diagonal struts worked before the outer frame inside the FTCW, forming a multistage energy consumption system for the design purpose of earthquake resistant structures. The numerical analysis results showed that the most effective way to improve the bearing capacity of RC frame-FTCW was to increase the amount of filled FTCW, followed by increasing the rebar ratio of frame columns, and the improvement of increasing the concrete strength or adding angle steel for the internal diagonal struts were smaller. The improvement of axial compression ratio on the bearing capacity was unnoticeable. In addition, the layout direction of FTCW was significant, and the number and position of FTCW should be symmetrically arranged.

The roughness of the interface between new and old concrete is one of the key factors that affect its shear performance. In this paper, the roughness of the new and old concrete interface is characterized and quantified based on fractal theory. Different fractal dimension interfaces of new and old concrete random aggregate geometric models are established using the Monte Carlo method and aggregate grading theory. By simulating the mechanical behavior of rough interfaces using zero-thickness cohesive elements locally embedded in the model, the effects of mesh size, random distribution of aggregates, fractal dimension, normal pressure, and interface material parameters on the shear performance of rough interfaces between new and old concrete are analyzed. The results show that the model's mesh size and random distribution of aggregates have no significant effect on the shear performance of the interface between new and old concrete. As the fractal dimension increases, the interface shear strength first increases and then decreases, and the fractal dimension corresponding to the maximum shear strength decreases as the normal pressure increases. Under the same fractal dimension, the shear strength increases linearly with the normal pressure. The normal pressure has a more significant impact on the interface shear strength compared to the fractal dimension. As the fractal dimension increases, cracks are more likely to propagate deeper into the old concrete area, and increasing the strength and fracture energy of the new and old interface can effectively improve the shear performance of the interface.