Control Mechanism and Experimental Study on Electric Drive Seed Metering Device of Air Suction Seeder

Under the condition of high-speed operation, the traditional mechanical seeder is easy to cause problems such as the drop of the qualified rate of sowing, the increase in the rate of missing sowing and the low precision of adjusting the grain distance, which seriously affects the sowing precision and efficiency. In this paper, a brushless DC motor sliding film variable structure control system is designed for the air-suction corn seeder, so as to realize the precise control of the rotation speed and the seed metering amount of the seed metering disc. The experimental results show that the faster the operation speed of the electrically driven air-suction seed metering device, the greater the standard deviation of sowing distance. The qualified rate of seeding, average spacing, standard deviation distribution and coefficient of variation of the electric seeding device are better than those of the mechanical seeding device

Hollow Multi-Shelled Structure with Metal-Organic-Framework-Derived Coatings for Enhanced Lithium Storage

Herein, we present heterogeneous hollow multi-shelled structures (HoMSs) prepared by exploiting the properties of the metal-organic framework (MOFs) casing. Through accurately controlling the transformation of MOF layer into different heterogeneous casings, we can precisely design HoMSs of SnO2@Fe2O3(MOF) and SnO2@FeOx-C(MOF), which not only retain properties of the original SnO2-HoMSs, but also structural information from the MOFs. Tested as anode materials in LIB&#39;s SnO2@Fe2O3 (MOF)-HoMSs demonstrate superior lithium-storage capacity and cycling stability to the original SnO2-HoMSs, which can be attributed to the topological features from the MOF casing. Making a sharp contrast to the electrodes of SnO2@Fe2O3 (particle)-HoMSs fabricated by hydrothermal method, the capacity retention after 100 cycles for the SnO2@Fe2O3 (MOF)-HoMSs is about eight times higher than that of the SnO2@Fe2O3 (particle)-HoMS.</p