Based on the porous medium theory and the continuum medium fluctuation theory，this paper studies the amplitude reflection and energy reflection properties of the plane P₁ wave reflection on the unsaturated semi-space free boundary. Using Helmholtz decomposition theorem and specific free boundary conditions，the analytical expressions of the amplitude reflection coefficient and energy reflection coefficient of four types of reflected waves （reflection P₁ wave，reflection P₂ wave，reflection P₃ wave，and reflection S wave） generated by the plane P₁ wave are obtained，and the effects of incidence and saturation，frequency and porosity on energetic properties is analyzed. The results show that the amplitude reflection coefficient and energy reflection coefficient not only are affected by the angle of incidence，but also have significantly changed with the change of saturation，and the reflected P₁ wave and reflected S wave carry the vast majority of the incident wave energy.

In order to apply active dry friction dampers （DFD） to the vibration control of rotor system，a model free adaptive force control scheme is proposed，where virtual feedback tuning method is exploited to tune the initial parameters. Vibration characteristics of the active DFD-rotor system are analyzed based on a two-dimensional dry friction dynamic model. And vibration control strategies are proposed to match the response characteristics of rotors. Then，a compact-form dynamic linearization model is applied to design model free adaptive control algorithm. Meanwhile，considering the cumbersome work of initial parameter tuning，a virtual reference feedback tuning procedure is used to initialize parameters for the controller and the rules to choose parameters used for off-line data generation is also discussed herein. In order to verify the efficacy of the proposed algorithm，a rotor system containing two discs is taken as the numerical example. Results reveal that，based on one single off-line parameter tuning procedure，the rotor vibration when critical speed is traversed can be efficiently controlled by the proposed control strategy. Meanwhile，for steady vibration control，the proposed strategy is able to adaptively apply controllable forces only if the vibration level is too large，in which case the unbalanced responses of rotors can be sustained within allowable range.

Based on the elastic foundation beam theory，the mechanical model for the seismic response of the vertical shaft is established. The shaft primary lining and secondary lining are simplified as Euler Bernoulli beams and the normal interaction between the primary lining and secondary lining is simulated by using uniformly distributed springs. The differential governing equations of the shaft under the horizontal seismic excitation are derived. The rapid solution of the horizontal seismic response of the primary lining and secondary lining is achieved through the distributed transfer function method and the correctness of the analytical solution is verified by comparison with the finite element numerical simulation method. The peak seismic response at the top of the shaft is parametrically analyzed from the perspectives of elastic foundation stiffness，secondary lining stiffness，shaft outer diameter，and stiffness of the elastic connection layer between the primary and secondary linings，respectively. The results show that the peak seismic response at the top of the secondary lining is greater than that of the primary lining. With the increase of the elastic foundation stiffness，the peak response of the top of the primary lining and the secondary lining decreases. The increase of secondary lining stiffness leads to the obvious increase of peak response at the top of secondary lining. With the increase of the shaft outer diameter，the peak response of both the primary and secondary linings increase significantly. When the elastic connection layer stiffness increases，the peak response of the primary lining increases slightly，but the peak response of the secondary lining decreases significantly.

A double Gamma distribution model to determine the probability density function （PDF） of the time domain rainflow-range corresponding to the broadband random stress power spectral density （PSD） is proposed，and a neural network method is used to implement the parameter prediction of the model. A series of stress PSDs are given，and the corresponding stress time histories are generated using the time-domain randomization method. The number of rainflow-range is counted for the stress time histories using the rainflow counting method，and the stress rainflow-range probability density values are calculated. Based on the calculation results of each stress PSD mentioned above，the proposed stress rainflow-range probability density double Gamma distribution model is parametrically fitted to obtain a set of corresponding model parameters. The results of the double Gamma distribution model are compared with the Dirlik method and fatigue life prediction is carried out，and the results show that the proposed double Gamma distribution model is more accurate for determining the broadband random stress rainflow-range PDF.

Aiming at the problem that the recognition accuracy of the model is not high due to the complex and variable engineering environment，a rolling bearing fault diagnosis model integrating Markov transition field and graph attention networks （MTF-GAT） is proposed in this paper. Using the advantage of MTF to retain the time correlation of the signal is applied to transform one-dimensional signals into two-dimensional feature maps，and the nodes and edges of the graph are defined. The graph attention layer can adaptively assign different weights to adjacent nodes to improve the ability of the model to capture useful fault features，and the abstract information of the graph is further extracted through the deep convolution module. By simulating the actual engineering environment，the various fault signals are input into the trained MTF-GAT model for fault diagnosis，and the model is verified by experiments on two data sets. The results show that the proposed model in this paper can accurately complete the task of fault classification in a variety of environments. Compared with other deep learning models，the MTF-GAT model has better recognition accuracy and generalization performance.

Plane irregular buildings are prone to torsion and cause serious damage to the structure. The analysis and control of structural torsion effect is the key to this kind of structural design. In this regard，the simulation calculation of the planar irregular multi-story frame model in the 8-degree fortification zone was carried out，and the planar L-type four-story frame isolation model of five typical class B buildings was established. The ratios of the length B and width W of the protruding limbs of the structure were set to be 1∶1，1.5∶1，2∶1，2.5∶1 and 3∶1，respectively. The dynamic characteristics and seismic response of different structures were analyzed. The influence of the LRB stiffness ratio and the rigid center position of the isolation layer on the structural torsion was discussed，and the effective control method of structural torsion was proposed. The results show that with the increase of the length-width ratio B/W of the protruding limb，the X-direction torsion of the structure increases gradually，and the Y-direction torsion decreases gradually. Increasing the proportion of LRB stiffness can reduce the torsional effect of the structure. By comprehensively controlling the structural torsion and structural damping coefficient，a reasonable proportion of LRB stiffness can be obtained. The proportion of LRB stiffness of the isolation layer under the condition of 8 degrees earthquake is proposed. At the same time，the rigid center of the isolation layer and the rigid center of the superstructure are arranged on both sides of the mass center of the superstructure to suppress the torsion of the superstructure of the plane irregular structure.

The full-field vibration displacement acquired via digital image correlation method is widely applied in aerospace structural testing and monitoring because of its advantages of high environmental adaptability and non-contact full-field. However，structural damage identification based on full-field vibration displacements faces two critical problems： Current modal analysis methods possess low computational efficiency when dealing with high spatial resolution displacement fields； The baseline-free damage identification method based on modal shape is difficult to extract damage features and has poor anti-noise performance. In order to solve those problems，a frequency domain modal analysis method based on kernel decomposition and joint principal component analysis，and a damage localization method based on pseudo-excitation are proposed. Singular value decomposition is employed to process the full-field displacement fields for obtaining the kernel functions and their coefficients，which contain the local damage characteristics. On this basis，a frequency domain modal analysis enhanced by joint principal component analysis is adopted to evaluate the noise-robust and high spatial resolution modal shapes. The disturbance of local dynamic equilibrium equation caused by structural damage is equivalent to a pseudo excitation force for damage detection. In addition，the local proximity of damage features and sparse spatial distribution of measurement noise are harnessed to optimize the damage localization accuracy via a hierarchical clustering method. Multi-modal information fusion damage index is proposed to improve the accuracy of damage localization. Numerical and experimental results demonstrate the effectiveness of the proposed method.

To achieve rapid recovery of structural function after the earthquake，based on the idea of replaceability and additional energy consumption，a new earthquake-resilient fully bolted beam-column joint is introduced in this study. The shortcoming of insufficient energy dissipation ability of the existing fully bolted joint loaded into large deformation condition is improved by setting up the T-shaped energy dissipator. The influence of the energy consumption length and slenderness ratio of the T-shaped energy dissipator on the seismic behavior of the new earthquake-resilient fully bolted joint is studied. Three new earthquake-resilient fully bolted joints and one welded joint were subjected to low-cycle loading. The results of tests show that the seismic performance of the new earthquake-resilient fully-bolted joint is better than that of the traditional welded joint. The new earthquake-resilient fully-bolted joint can concentrate the plasticity and damage，transfer the plastic zone to the T-type energy dissipation plate，and avoid the fracture of the welding zone at the beam end. In this paper，the lower limit of the length of the energy dissipation segment is given. When the energy dissipation segment has sufficient deformation length，and the cross-section area of the energy dissipation section is the same，the conservative slenderness ratio is determined to be 13.2，which can make the new joints have good bearing capacity and ductility，and give full play to the seismic performance of the new joint.

To address the issue of carrying rolling element bearing （REB） fault diagnosis where the conventional vibration sensor is difficult to install，an instantaneous angular speed （IAS） signal based REB fault diagnosis method by optimized AR model is proposed. The forward differential method is used to calculate and estimate the instantaneous angular speed signal. Then，the biased estimation autocorrelation analysis is used to determine the optimal order p by the maximum autocorrelation kurtosis. Periodic components in the IAS signal are removed by AR prediction，and the residual components containing rich bearing fault information are remained. The residual components are pre-whitened to equalize the importance of each band and to extract fault characteristics from the envelope. Simulation signal and outer ring data from a test rig validate the effectiveness of the proposed method. The experimental comparative analysis results show that the calculation efficiency is improved significantly when compared to the existing method of fast spectral steepness combined with order analysis based on vibration signal.

A vibration-controlled device with paired inclined nozzles is designed to reduce the barrel vibration and minimize the impact on the aircraft during continuous firing. The newly designed paired inclined nozzles generate only dynamic moment and recoil force，without producing transverse force. An interior ballistics model of the barrel with lateral channels is established，and the TVD-MacCormack difference scheme is utilized to numerically calculate the flow field in the barrel and the time-dependent aerodynamic force of the nozzles. Dynamic simulations of the continuous firing process of the aircraft gun are conducted to evaluate the effect of the paired inclined nozzles on the muzzle vibration. Results show that the time difference of the maximum aerodynamic force of the two nozzles is 0.07 ms，with a relative difference of the maximum aerodynamic force of only 0.5%. This indicates that the two nozzles are well synchronized. The paired oblique nozzles can greatly reduce the muzzle vibration without compromising the initial velocity of the projectile. The linear displacement and velocity of the lateral vibration decrease by 26.9% and 44.3%，respectively. The recoil momentum also decreases by 17.93%，without generating transverse force on the aircraft. As a result，the impact on the aircraft is significantly reduced. The achievements of this research will support the design of aircraft gun barrels with paired inclined nozzles.