The time-varying mesh stiffness is a core parameter of gear systems，and the mesh stiffness identification is of great significance for the dynamic analysis and condition monitoring of gear transmission systems. Since it is difficult to directly measure the mesh stiffness，it is necessary to develop a data-driven time-varying mesh stiffness identification method. To deal with this problem，an alternating state-parameter optimization method is proposed to identify the time-varying mesh stiffness of gear systems. The Fourier series with the fundamental frequency of the mesh frequency is constructed to characterize the mesh stiffness. Furthermore，a Reproducing Kernel Hilbert Space （RKHS）-based de-noise method is further proposed to estimate the system state and parameter. The system state and stiffness parameter are alternately optimized with the joint constrains of dynamic model and data to realize the time-varying mesh stiffness identification of gear transmission systems. The simulation and experimental studies validate the effectiveness of the new mesh stiffness identification method for gear systems.

Spinning cylindrical shells are critical components in practical engineering structures. The boundary conditions at the shell ends are diverse and significantly influence the vibration characteristics of the shell. To study these characteristics under various boundary conditions，a dynamic model of the spinning cylindrical shell is established using Lagrange equations and Novozhilov’s shell theory. The mathematical description of the boundary conditions for the cylindrical shell is combined with the discretized displacement functions，which are constructed based on a linear combination of Chebyshev polynomials. These functions satisfy the boundary conditions and are independent of the cylindrical shell's parameters. The vibration characteristics of stationary cylindrical shells are determined by solving the eigenvalue problems，revealing the influence of rotary inertia on the vibration characteristics. The applicability of different shell theories with respect to various geometrical parameters of the shell is discussed. Additionally，circumferential wave-dependent mode functions are identified and used to compute the natural frequencies of shell modes with the zero circumferential waves，as well as the travelling waves of the spinning cylindrical shell under different boundary conditions. The impact of structural parameters on the natural frequencies of the travelling waves is also analyzed.

Direct measurement of dynamic loads on engineering structures is challenging due to environmental constraints. Therefore，the indirect identification or reconstruction of dynamic loads，using dynamic response information，has emerged as a highly effective method. Over decades，dynamic load identification has evolved，resulting in a series of valid solutions. This paper begins by reviewing the research history and main achievements of dynamic load identification methods. It provides a systematic exposition of typical frequency domain and time domain methods，as well as dynamic load identification methods which are based on various approaches such as function fitting，regularization strategies，Bayesian frameworks，and data-driven techniques. The advantages and disadvantages ，as well as application scope of each method，are also discussed. Additionally，this paper summarizes common issues in the load identification process，including uncertainties in structural parameters and input conditions. Identifying the position of dynamic loads is also a crucial aspect of the dynamic load identification problem. This paper analyzes the methods currently available for position identification. This paper delves into the engineering applications of dynamic load identification methods and analyzes the limitations of current methods. Considering the current challenges in the field of dynamic load identification and the increasing demands in practical engineering applications，the paper anticipates the technical difficulties that need to be addressed. It also discusses potential future development directions and key areas in dynamic load identification.

A novel vibration method，the master-slave distributed vibration test method，was proposed. Aiming at its control requirements，an online waveform replication technique for vibration loads was developed and an integrative prototype system with measuring and controlling functions was constructed. Therein，a signal processing method of frame segmentation and reconstruction was proposed for solve the problem that time waveform replication for long-duration continuous vibration loads. A method for dynamic transfer function estimation based on sample database construction and weighted average was proposed to reduce the influence of nonlinear property on control precision. A spectrum correction method was introduced to improve the frequency domain control accuracy. A test with 1 master vibrator and 2 slave vibrators was performed using the developed online vibration load replication control technique，and the results show that the technique has a high replication precision in both time domain and frequency domain，has a subsecond overall delay time，and has a subpercent overall root-mean-square error. The technique can provide a key technique for supporting online distributed vibration tests.

Floating raft vibration isolation systems in the ships or submarines have the requirement of low weight and small volume. To reduce the weight of floating raft vibration isolation systems and improve its vibration suppression effect，nonlinear energy sink cell （NES cell） is applied to the structural optimization of the floating raft vibration isolation system. NES cells are placed on all the substructures of the floating raft system. The mechanical model of the floating raft system with four degrees of freedom and the vibration damping system with NES cell are established. The modal analysis of the floating raft system is carried out. The approximate analytical expression of steady-state response for nonlinear system is derived by Harmonic balance method （HBM） and verified by Runge-Kutta （RK）. The vibration suppression effect under the different total weight and NES cell number is compared by force transitivity response，and the influence of the NES cell number and total weight of the system for the 1st-order mode is analyzed. The results show that NES cell can effectively improve the vibration suppression efficiency of the floating raft system for all the modes while reducing the total weight of the system and realize the structural optimization of the floating raft system effectively.

In order to suppress the nonlinear vibration during the motion of a flexible manipulator，a model-free hybrid control strategy of trajectory tracking and vibration suppression based on a novel online observation of disturb forces is proposed. The Lagrange equation and singular perturbation method are employed to model and decouple the dynamics of the manipulator，which are decomposed into a slow subsystem representing rigid motion and a fast subsystem representing flexible vibration. Considering the complexity of modeling and uncertainty of model parameters，PD control method is adopted to realize trajectory tracking，and model-free adaptive control algorithm is proposed to realize nonlinear vibration control of flexible links. To solve the control divergence problem caused by unknown external disturb forces，a modified extended state observer is proposed to online estimate and real-time compensate the disturb force，which can improve the convergence performance of model-free vibration control algorithm effectively. The simulation results show that the proposed method can effectively suppress the vibration of the flexible manipulator in the presence of disturb force，and has good dynamic performance and robustness.

This paper investigates the dynamics and control problems of the long-term deorbiting of an electrodynamic tethered satellite system. The dynamics modeling of the system is carried out based on a dumbbell model assumption. To improve the accuracy of the system model，the orbital dynamics is described using a set of modified equinoctial elements，involving the effects of Lorentz force，atmospheric drag and J₂ perturbation force. Three current control strategies are proposed to regulate the electrodynamic forces for achieving a stable long-term deorbiting process，namely，the constant current input，the directionally variable current input，and the optimal control strategies. In the design of the optimal control strategy，the long-term deorbiting problem is formulated as an inverse problem of dynamics with nonlinear constraints，which is further solved via a nonlinear programming method to obtain the optimal reference trajectories. The deorbiting of the system is then achieved using the modified current control input obtained from a tracking feedback control law. Additionally，an energy-based current switch control strategy is adopted to ensure the stability of system and the efficient utilization of Lorentz force. Case studies of the system with designed physical parameters are conducted to analyze the deorbiting efficiency and to validate the effectiveness of the proposed control strategies.

At present，the big aviation countries already have mature gust wind tunnel test technology，but which is relatively backward in China，especially the gust wind tunnel tests equipment and technology of full aircraft model are lack. In this paper，a gust generator，a five-degree-of-freedom suspension system and a full elastic aircraft model are developed，and the wind tunnel tests of the whole model are carried out. The test results show that the gust field is stable，and the deviation of the gust velocity between the two ends and the center of the wind tunnel is less than 25%. The support stiffness of the model suspension system is small and the stability is good，which can meet the requirements of the gust wind tunnel test. The simulation results of the non-uniform gust field are close to those of the wind tunnel test，and the error of the moment of the wing root is less than 15%，and the error of wing tip overload is less than 0.2g.

This paper considers a quadrotor transportation system with a four-cable-suspended payload. The relative position between quadrotor and payload is introduced and used to derive the tension of cables and describe the transportation system. A cost function inspired by payload and time is built to equipoise rapid UAV positioning and payload swing elimination. Then，the pseudo-spectral method is applied to transform the optimal control problem into a nonlinear programming problem and solve the optimal trajectory. A quadrotor transportation system’s trajectory tracking is facilitated by a PID controller. The optimal trajectory is validated through the presentation of both simulation and experimental results at last.

The study of the influence of potential well parameters on the output of a nonlinear energy harvester system is conducive to the design of the high-performance energy harvester system. Meanwhile，the stochastic resonance phenomenon in the corresponding electromechanical coupling dynamics model of the energy harvester system can be used to enhance the characteristics of weak faults，so as to effectively identify weak faults. This paper proposes a decoupled saddle-point-degradation bistable potential function，and the electromechanical dynamic model is introduced. The bifurcation diagram under different excitation amplitudes is obtained to discuss the effect of the barrier width and the barrier height on the responses （periodic response and chaotic response）. According to the methods of the Poincaré map，the frequency spectrum analysis，and the Lyapunov exponent，the periodic response and the chaotic response are examined at a fixed excitation amplitude，which is consistent with that obtained from the bifurcation diagram. Based on the electromechanical dynamic model perturbed by the random noise，the stochastic-resonance-based method is proposed for fault diagnosis，which achieves the enhancement of the simulated and experimental bearing fault characteristics.