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Graphical abstract Host-1 and drugs combination and in vivo release concept. Abstract The targeted or responsive systems are appealing therapeutic platforms for the development of next-generation precision medications. So, we design and prepare acid-controlled release complexes of podophyllotoxin (POD) and etoposide (VP-16) with pH-labile acyclic cucurbit[ n ]urils, and their characteristics and inclusion complexation behaviors were investigated via fluorescence spectroscopy, nuclear magnetic resonance and X-ray power diffraction. Cells incubated with complexes have been analyzed by high-content analysis (HCA), and cytotoxicity tests have been completed by MTT assay. The results showed that complexes with different binding constants can release the drug substance in the physiological pH environment of cancer cells, maintain good anticancer activity, and have low cytotoxicity. This provides a strategy about targeted and responsive systems of POD and VP-16 for clinical application. [ABSTRACT FROM AUTHOR]

The offshore wind turbine is a device that uses the wind energy on the ocean to generate electricity. The voltage generated by offshore wind turbine can break down the insulated bearing and cause inclined shaft current damage. To explore the dynamic characteristics and influencing factors of offshore wind turbine rotor system, a dynamic model of offshore wind turbine rotor system is proposed. The insulating coating, inclined shaft current damage and contact characteristics are considered in the model. Through numerical simulation, the mapping relationship between vibration response and damage length is studied, the influence of the interaction between inclination angle and radial clearance on vibration response is analyzed, and the influence of the mass of insulating coating and speed on vibration response is discussed. The practicability of the model is proved by the experiment of physical prototype. The results show that, as the length of the shaft current damage increases from 10 × 10−5 m to 50 × 10−5 m, the strength of the vibration response increases. The coupling of the inclination angle of the shaft current damage and the radial clearance jointly promotes the enhancement of the vibration response. The enhancement effect of radial clearance is more significant than that of inclination angle. The increase of speed worsens the state of operation, and the state transitions from stable quasi-period to chaos. • A novel dynamic model of offshore wind turbine rotor system is established. • The mathematical model characterizing the inclined shaft current damage is considered. • The influence of insulation coating and shaft current damage on the vibration is analyzed. • The influence of the coupling of damage and radial clearance on the vibration is studied. [ABSTRACT FROM AUTHOR]

The nonlinear behaviors of the shaft-bearing-pedestal system considering damage of cylindrical roller bearing are analyzed in this study. Firstly, the model of the shaft-bearing-pedestal system with damaged cylindrical roller bearing is explored and the dynamic modeling is completed. The dynamic equations are solved by numerical method, and the nonlinear responses of the system are obtained. Then, the model is verified by comparing the experimental measurement signal with the numerical simulation value. Finally, the nonlinear behaviors under different loads, different damage sizes and different shaft speeds are studied. The results indicate that the peak to peak value of the vibration signal is positively correlated with the load F. As the load changes in the range of 100 N to 260 N, the system bifurcates from chaotic motion to 3T-periodic motion, and transits the chaotic motion through quasi-periodic 3 motion. The bifurcation diagram of the shaft-bearing-pedestal system shows complex nonlinear behavior, and bifurcation and jump behavior alternate. Properly increasing the load of the system during high-speed operation will contribute to improve the stability of the system. • A dynamic model of shaft-bearing-pedestal system considering damage is established. • The mathematical model characterizing the damage of the bearing raceway is considered. • The bifurcation, jump and chaos of the shaft-bearing-pedestal system are analyzed. • The vibration responses of the system under different working conditions are studied. [ABSTRACT FROM AUTHOR]

• Dynamic model of a flexible manipulator considering two-dimensional deformation and friction torque is established. • Analyze the influence of the nonlinear terms in the dynamic model on the deformation. • Combined control method of sliding mode control and fuzzy compensation to control the flexible manipulator. • 4.Flexible manipulator control experiment platform verify the correctness of the model and control strategy The flexible manipulator servo system considering the second-order modal and two-dimensional deformation is too complicated, which is not conducive to real-time control. In order to establish dynamic equations that can be controlled in real-time, it is necessary to analyze each nonlinear factor. Based on the results of dynamic analysis, a model simplification method is proposed that ignores the second-order modal deformation. What's more, an improved fuzzy compensation sliding mode control (FCSMC) strategy is proposed to control the angular velocity of the servo system. The friction torque and the ignoring nonlinear factors are compensated by the fuzzy systems. The improved FCSMC strategy can reduce the chattering phenomenon and the angular velocity errors. Simulation experiments and physical control experiments prove the effectiveness of the improved FCSMC strategy. The results show that the improved FCSMC strategy has smaller angular velocity errors. Therefore, the strategy can effectively improve the movement accuracy of flexible manipulators, which is conducive to the precise end-effectors. [ABSTRACT FROM AUTHOR]

The dual-inertia system with a flexible load (DSFL) is a complex nonlinear model, which originates from the flexible load deformation and payload mass variation. In dynamic modeling, it is impossible to consider all the nonlinear factors, including high-order modes and inaccurate friction torque, which leads to the existence of uncertain components in the DSFL. Based on this, it is impossible to build a dynamic model of the DSFL that is completely consistent with the real physical model. This modeling errors increases the tracking errors of the DSFL. In this study, the neural networks are employed to recognize the lumped uncertain components of the DSFL dynamic model, so as to reduce the flexible load's tracking error. Firstly, based on the deformation accuracy comparison, a relatively high precision model simplification method is proposed, which neglects the second order mode. Next, the control law of the neural network identification control strategy is designed according to the stability theorem. Finally, through physical control experiments and simulation analysis, it is shown that this control strategy enhances the motion accuracy of the DSFL. The experimental results show that this control strategy predicted by the radial basis function (RBF) neural network can reduce the rotation angle error by 15.86%. [ABSTRACT FROM AUTHOR]

Achieving stable and high-precision control of underwater manipulators in complex ocean environments is one of the biggest challenges faced by the research of marine robotics at present. Flexible link manipulators can be installed on unmanned underwater vehicles to realize underwater operations such as underwater cable inspection, deep sea rescue, and marine organizational collections. The flexible link underwater manipulator will vibrate due to the influence of torsional flexibility and water flow disturbance during rotation, which will seriously affect the motion accuracy of the end actuator. In this paper, a control strategy combining the adaptive proportional-integral (PI) controller and the nonlinear disturbance observer is proposed, which indirectly suppresses vibration by improving the speed control accuracy. Firstly, according to the assumed mode method, a dynamic model of the flexible link underwater manipulator considering torsional flexibility and external disturbance is established. Next, the overload compensation control law is proposed to meet the closed-loop stability of the flexible link underwater manipulator. In addition, the PI controller's adaptive law is designed according to the Lyapunov theorem. Finally, the effectiveness of the adaptive PI controller with a nonlinear disturbance observer is proved by the simulation and control experiments of different control strategies. The results show that the proposed controller can achieve stable speed tracking and has a better vibration suppression effect. • Dynamic of flexible link underwater manipulators is established. • Nonlinear disturbance observer is proposed to reduce disturbance. • Adaptive PI control strategy with nonlinear disturbance observer to suppress vibration. • The overload compensation control law is used to ensure the closed-loop stability. [ABSTRACT FROM AUTHOR]

• Dynamic model of a dual-flexible servo system considering two-dimensional deformation is established. • Influence of the nonlinear terms and friction torque in dynamic equations is analyzed. • Control law of the neural network sliding mode controller is designed to identify the uncertain part. • Experimental platform of the dual-flexible servo system is built to carry out control experiment. A variable-length dual-flexible servo system is a complex nonlinear system that consists of a servo motor, a flexible joint, and a variable-length flexible load. In order to describe the mechanical behavior of the servo system more accurately, the two-dimensional (2D) deformation of flexible load needs to be considered. The coupled nonlinear terms, friction torque, and time variation of parameters in the dynamic equations constitute the uncertain part of the servo system. These mentioned factors will cause fluctuations in the flexible load's rotation angle. In this paper, a sliding mode control strategy based on neural network compensation is proposed to control the servo system. Firstly, the dynamic equations of the dual-flexible servo system considering the 2D deformation are established according to Lagrange's theorem. Then the control law of the sliding mode controller based on neural network is designed. The adaptive law of weight coefficients in the neural network is designed by the Lyapunov stability theorem. Finally, the numerical simulation analysis and control experiments are carried out. The experiment results prove that the control strategy can reduce the tracking error by 43.6%. [ABSTRACT FROM AUTHOR]