In precision seeding, the final displacements of the seeds are determined as a working result of the profiling mechanism, opener, seed-metering device, covering apparatus and compacting machine. For a better understanding of the disturbance of seed displacement during soil covering and compaction in the actual working process, experiments and simulations have been performed. In this paper, a type of soybean seeding monomer was taken as the research object, and a soil bin test of soil covering and compacting was executed. The experimental results showed that the traction velocity and the open angle of the covering discs had a significant influence on the changes in the horizontal and vertical displacements of seeds during the soil covering processing. With an increasing traction velocity, the vertical displacements of seeds increased after soil covering; in contrast, the horizontal displacements decreased. When the covering apparatus had a larger open angle it had a smaller disturbance influence on the soil. Therefore, with an increase in the opening angle, the changes in the vertical and horizontal displacements of seeds showed a decreasing trend. Inversely, in the process of compacting, the forward velocity had little effect on the three-dimensional displacement change in the seeds after compacting. The analysis model of the precision seeding unit was established based on the coupling model of the DEM (discrete element method) with MBDs (multi-body dynamics). The process of soil covering and compacting was simulated and analyzed. The comparison between the experimental results and the simulated results showed that the trend was similar, and the two results were close. Thus, the feasibility and applicability of the coupling method were verified. It also provided a new method for the design and optimization of covering and compacting components of a precise seeding monomer.

To study the saline-alkali migration law of soda saline-alkali soils based on sub-soiling technology, improve the soil quality of soda saline-alkali agricultural area, and provide scientific basis for the construction of high and stable yield fields of crops in soda saline-alkali soils. Based on the unsaturated soil water movement theory and the convection-dispersion theory of solute transport in porous media, a single-parameter and two-parameter model of saline-alkali transport was constructed to analyze the distribution of saline-alkali concentration in soil solution with the depth of soil layer. Soil samples were taken from four soda saline-alkali soils in different periods under sub-soiling tillage. The experimental data of soil saline-alkali content were obtained, and the law of saline-alkali migration was analyzed. When the depth was 60 cm, the content of saline-alkali in the soil before breaking the plough bottom was 0.4%, and the content of saline-alkali was 0.35% after breaking the plough bottom with sub-soiling technique. It can be seen that sub-soiling technique can promote saline-alkali infiltration and reduce the content of saline-alkali in the planting soil layer. The average water content of the sub-soiled soil was 23.4%, which was significantly higher than that of the subsoiled soil. The soil salinity and alkali content in 100 cm depth layer decreased by 30.8%, and that in 40 cm depth layer decreased by 57%. The salinity and alkali data in different regions showed that the soil salinity and alkali content in the soil decreased by 30.8%. Saline-alkali data from different regions show that due to sub-soiling, salt-alkali in the soil moves upward, salt-alkali in the lower part of crop roots moves outward, and salt-alkali in the soil moves away from the crop root zone; between 0 and 50 cm under the soil, the content of soil salt and alkali is from small to large, forming a desalination area of saline and alkali content; sub-soiling tillage makes 0-30 cm layer soil desalinization rate reach 83.5%, the soil salt removal rate of 0-60 cm layer reached 79.9%; The effect of sub-soiling on soil salinity is less than 1.634% of the initial value. Conclusion: sub-soiling technology can effectively reduce saline alkali content and increase crop yield in soda saline alkali soil.

Focusing on the bottlenecks of traditional physical activation method for the preparation of activated carbons (ACs), we established a simple and scalable method to control the physicochemical structure of ACs and study their CO2 adsorption performance. The preparation is achieved by ammonia activation at different volume fractions of ammonia in the mixture (10%, 25%, 50%, 75%, and 100%) to introduce the nitrogen-containing functional groups and form the original pores and subsequent chemical vapor deposition (CVD) at different deposition times (30, 60, 90, and 120 min) to further adjust the pore structure. The nitrogen content of ACs-0.1/0.25/0.5/0.75/1 increases gradually from 2.11% to 8.84% with the increase of ammonia ratio in the mixture from 10% to 75% and then decreases to 3.02% in the process of pure ammonia activation (100%), during which the relative content of pyridinium nitrogen (N-6), pyrrolidine (N-5), and graphite nitrogen (N-Q) increase sequentially but nitrogen oxygen structure (N-O) increase continuously. In addition, ACs-0.5 and ACs-0.75, with a relatively high nitrogen content (6.37% and 8.84%) and SBET value (1048.65 m2/g and 814.36 m2/g), are selected as typical samples for subsequent CVD. In the stage of CVD, ACs-0.5-60 and ACs-0.75-90, with high SBET (1897.25 and 1971.57 m2/g) value and an appropriate pore-size distribution between 0.5 and 0.8 nm, can be obtained with the extension of deposition time from 60 to 90 min. The results of CO2 adsorption test indicate that an adsorption capacity of ACs-0.75-90, at 800 mmHg, is the largest (6.87 mmol/g) out of all the tested samples. In addition, the comparison of CO2 adsorption performance of tested samples with different nitrogen content and pore structure indicates that the effect of nitrogen content seems to be more pronounced in this work.

In this paper, the Multisphere (MS) models of three varieties of Cyperus esculentus seeds are modeled based on DEM. In addition, for comparison, other particle models based on automatic filing in EDEM software are also introduced. Then, the direct shear test, piling test, bulk density test, and rotating hub test are used to verify the feasibility of particle models of Cyperus esculentus seeds that we proposed. By comparing the simulated results and experimental results, combined with the CPU computation time, the proposed particle models achieved better simulation accuracy with fewer filing spheres. According to simulation results, some limitation was present when using one single verification test; varieties of verification tests used could improve the verification reliability, and a more appropriate particle model could be selected. Additionally, the issue of multicontact points in the MS model was studied. The Hertz Mindlin (no slip) (HM) model and Hertz Mindlin new restitution (HMNR) model were both considered in simulations for comparison. The rotating hub test and particle–wall impact test were used, and the influences of multiple contact points on the motion behavior of individual particles and particle assemblies were analyzed. Simulation results showed that the multiple contact points affected the motion behavior of individual particles; in contrast, the influence of multiple contact points on the motion behavior of the particle assembly was insignificant. Moreover, the relationships between moisture content of seeds and Young’s modulus, Young’s modulus, and the number of contact points were also considered. Young’s modulus decreased with increasing moisture content. The number of contact points increased with a decreasing Young’s modulus.

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