The 3K planetary gear system is a basic planetary transmission structure with many advantages over the 2K-H planetary gear system. However, the vibration characteristics will be more complicated due to the increase of central gears meshing with each planet gear simultaneously. In this paper, a lumped-parameter model for a 3K-II planetary gear set was developed to simulate the dynamic response. The time-varying stiffness of each meshing pair for different gear tooth root crack faults is calculated via the finite element method. By considering the effect of time-varying transmission paths, the transverse synthetic vibrations are obtained. Subsequently, the feasibilities of transverse synthetic vibration signals and output torsional vibration signals as reference for fault diagnosis are analyzed by studying the time-domain and frequency-domain characteristics of these two vibration signals. The results indicate that both the transverse synthetic vibration signals and output torsional vibration signals can be used for fault identification and localization of the 3K-II planetary gear train, and yet they both have their limitations. Some results of this paper are available as references for the fault diagnosis of 3K planetary gear trains.

A damping fuzzy proportional-integral-derivative (PID) control method for electronically controlled air suspension shock absorbers was proposed to reduce the RMS values of the body vibration acceleration and improve vehicle ride comfort. Depending on the operating mode of the electronically controlled air suspension shock absorber, a mechanical model of the air suspension shock absorber was established. A fuzzy PID control technology for damping control of the shock absorber is designed by combining a PID control algorithm with the fuzzy control concept. The adaptive expansion factor of the cybernetics domain for the fuzzy PID controller is calculated by considering nonlinear characteristics and time delay to improve the controller’s adaptability. Then, the control parameters are adjusted based on the control deviation and deviation rate parameters. The nonlinear detection platform produced by an enterprise is selected to build an experimental environment for analysis. Simulation results reveal that when the vehicle speed is 30 km h⁻¹, the RMS values of the body vibration acceleration upon applying the proposed method is approximately 0.02 and 0.05 km h⁻², respectively, on Class B and C road surfaces. Furthermore, the RMS values of the body vibration acceleration using the proposed method has little fluctuation; when the vehicle speed is 60 km h⁻¹, the RMS values of the body vibration acceleration is 0.022 and 0.028 km h⁻², respectively, on Class B and C road surfaces, indicating that the proposed method can effectively reduce the RMS values of the body vibration acceleration and improve rider comfort.

Metal–organic frameworks have been a new type of adsorbent in environmental remediation due to their simple preparation processes and stable chemical properties in water. However, they are limited by their low adsorption capacities to some organic pollutants. Herein, ZIF-67 nanoparticles with a high Brunauer, Emmett and Teller (BET) surface area were designed and successfully synthesized by a time-saving, low cost, and environment liquid phase synthesis method at room temperature. The physicochemical properties of ZIF-67 nanoparticles were well studied by various measurements, such as x-ray diffraction, BET analysis, and scanning transmission microscopy. Meanwhile, the ZIF-67 nanoparticles with the stable structure are introduced as the adsorbent for trapping brilliant green in pollutant water, exhibiting the ultra-high adsorption capacity of 1989 mg g⁻¹ due to their high specific surface area (425 m² g⁻¹) and the interaction between π–π and the benzene ring. Moreover, the ZIF-67 showed acceptable reusability after regeneration with ethanol. Evidently, the ZIF-67 nanoparticles show excellent adsorption performances for organic dyes. This work can give a new application to zeolite imidazole framework materials in water treatment.

As the early fault features of tooth surface spalling are very weak and difficult to extract because of random noise and other types of signal interference, a method that combines maximum correlation kurtosis uncoiling and variational mode decomposition is proposed herein. First, a series of modes are obtained by variational mode decomposition, and the kurtosis criterion is applied to select the modes containing rich fault information for reconstruction and noise reduction. Second, the maximum correlation kurtosis deconvolution method is used to enhance the selected signals. Finally, the fault features are extracted by envelope demodulation of the reconstructed signal. The effectiveness of the proposed method is verified by analysis, and the different frequency components of the vibration signals of tooth surface spalling faults are shown to be separated accurately.

This study considers the tooth spall morphology and establishes a kinetic model of a high contact ratio gear pair system with an ellipsoid tooth spall defect. The mesh stiffness of the spalled gear system is evaluated using the potential energy method. To obtain the accurate dynamic response, the friction force was incorporated into the gear kinetic model. The dynamic transmission error and dynamic meshing force under different rotational speeds are acquired by the proposed model. The dynamics of a healthy gear system and spalled gear system was compared. The results reveal that the presence of the tooth spall defect alters the motion state of the system, making it prone to instability. The study provides a theoretical foundation for future research on spall defect diagnosis of gear transmission devices.