No abstract

With the development of automobile technology, the traditional passive suspension cannot meet people’s requirements for vehicle comfort and safety. For this reason, a variable damping semi-active suspension applied magnetorheological damper is proposed. By collecting various performance parameters of the front suspension, the optimal feedback control matrix is obtained by applying linear quadratic Gaussian control strategy, and the optimal damping force output is also obtained to improve comfort and vehicle safety by reducing vibration. The semi-active suspension model of a quarter vehicles was established by MATLAB/Simulink, and the simulation experiment was carried out. The results show that the semi-active suspension system with magnetorheological damper is superior to the traditional passive suspension in terms of vibration absorption; meanwhile, the root mean square values of vehicle acceleration, suspension dynamic deflection, tire dynamic travel, and tire dynamic load are reduced, which effectively improve the vehicle ride stability.

Multiple linear regression is used on establishing a prediction model of surface roughness in cylindrical grinding, according to systematic analysis and testing. The nearly relationship between surface roughness and operating parameters(such as workpiece speed ,wheel speed , grinding depth and vertical feed ) is more deeply revealed .It is showed that the model has simple structure and well predictive capabilities by the significant testing and examination. The model will provide a reliable basis for intelligent control and virtual manufacturing ,and achieve the purpose of precise control of the grinding process.

For a sustainable energy harvesting method, triboelectric nanogenerator (TENG) is becoming more and more important in natural wind energy harvesting. However, harvesting capacity of the TENG is affected by the low frequency of natural wind. To effectively harvest wind energy, a frequency-enhanced triboelectric-electromagnetic hybrid generator (FE-TEHG) is proposed, which integrates generation units. It contains a cam structure with six noses to increase the frequency of the wind. And in the generation units, the TENG module is integrated into the follower, and the electromagnetic generator (EMG) module is integrated into the driving part. Experiments proved that by increasing the input frequency, the output electrical signal of the TENG module becomes six times the original, and this integration method can greatly improve the output capacity of the generator. In the process of charging a 100 μF capacitor to 1.50 V, the charging speed of the FE-TEHG is 1.58 times that of the TENG module. In addition, when the wind speed is about 9 m/s, the FE-TEHG can light up 640 light-emitting diodes (LEDs) and supply power for a thermometer normally. Therefore, this paper provides a valuable method for frequency enhancement and integrated design of the TENG in wind energy harvesting.