High light absorption property based on the resonant nanostructures of butterfly Heliophorus ila Lvcaenidae wing scales.
The physical and mechanical parameters of the rotten rice straw (RRS), rice husk biochar (RHB), and the mixture of the two materials (the substrate) were calibrated by Plackett-Burman and Box-Behnken experiments to obtain the parameters for simulation of the forming of the Gentiana seedling substrate mat (GSSM). The particle contact parameters were calibrated, and the repose angle was taken as the response value based on the Hertz-Mindlin approach with the JKR contact model of discrete element method (DEM). A quadratic regression model was established and optimized using Design-Expert software. The parameters that most affected the substrate repose angle were the restitution coefficient of RRS of 0.20, the rolling friction coefficient of RRS of 0.04, the surface energy of RRS for JKR of 0.53, and the surface energy of RHB-RRS for JKR of 2.11. The simulated repose angle of the substrate and the bending strength of GSSM were compared with that of the verified experimental values respectively based on the optimal parameters. The relative errors of repose angles and bending strengths between the values of the simulation and the measurement were 0.71% and 1.39% respectively, indicating that the parameters obtained in this study can provide a reliable reference for the forming of GSSM.
Instead of compressing biomass into briquettes, this study considers the compression of biochar. Densification is necessary for biochar to increase bulk density for convenience of handling, transportation, and storage. Response surface methodology was employed, and briquetting of biochar from corn stover was carried out in this study to investigate the effects of moisture content (at levels of 16, 17.6, 20, 22.4, and 24%), pressure (at levels of 21.5, 25, 30, 35, and 38.5 MPa), and residence time (at levels of 4, 6.4, 10, 13.6, and 16 s), on crushing resistance, dimensional stability of briquettes, and specific energy consumption of briquetting. The results showed that the effects of the variables on each evaluation index were significant (P < 0.01), the influence order was obtained, and the regression models are set up. The optimum condition for the briquetting process was moisture content of 18.5%, pressure of 38.5 MPa, and residence time of 4 s, giving mean values of the briquette crushing resistance of 49.9 N, dimensional stability of 93.8%, and specific energy consumption of briquetting of 4.41 MJ/t, respectively. The errors between the predicted values and the experimental values are all less than 5%.
In order to realize the technology of mechanized mulching planting in paddy field, the flow of surface soil in paddy field was simulated by using Fluent software, and the flow of air and mud during parallel slide of equipment in two-phase fluid medium of air and mud was studied. The simulation method of the two-phase flow was determined, and the two-phase diagram of air and mud and velocity and pressure diagrams of fluid around the model were obtained. The mud around the model was divided into four regions Mq, Mc, Mx, Ms. Based on this, the structural parameters of the mulching system were optimized. At the speed of 1.65 m / s and the viscous coefficient of 2.72kg/m• s, Fluent was used in simulation analysis and experimental verification of the four models of soil-engaging equipment in the optimized paddy field mulching system. The results show that: the increase of α, β (vertical inclination angle α = 150 ° and end embedded angle β = 150 °) can significantly improve the traction resistance and mud obstruction of the equipment. The relative error of the traction resistance of four models of cylindrical roller, elliptical roller, ejector plate and ship plate was 8.3%, 10.27%, 6.67% and 13.74% respectively. The simulation results are in good agreement with the experimental data, which verifies the reliability of the model and provides a new research method for the study on surface soil of paddy field.
In view of high center of gravity and poor stability of traditional corn harvesters, a corn combine harvester frame is designed for hill and mountain operations based on TRIZ theory. The frame supports engine mode of middle engine rear drive, consisting of a front frame and a rear frame. The tail of the front frame is welded under the head of the rear frame. The front frame has reduced height and increased width to allow lower center of gravity and better stability of the whole machine. The left and right longitudinal beams of the front frame have different heights to allow better trafficability of the whole machine. A 3D model is established using Solidworks software and incorporated with ANSYS software to perform finite element analysis and modal analysis on the frame. It turns out that under full-load bending and full-load torsion conditions, the frame strength and stiffness meet the mechanical performance requirements, and the frame displays fine dynamic characteristics. According to the analysis results, the frame is optimized under the goal of light weight. While the frame strength and stiffness requirements are met, the frame mass is lowered by changing the frame component thickness. After optimization, the entire frame volume is reduced by 14.27%, with mass reduced by 14.3%, and the strength and stiffness conform to the requirements, thus achieving lightweight optimization of the frame.Moreover, The stability analysis of the corn combine harvester shows the overturning angle of uphill is 45.3°, the overturning angle of downhill is 45.7°, and the overturning angle of slopel is 40.2°.
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