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Transplanting is the prime growing pattern for rice production, and seedling raising is an essential step of the process. However, the massive soil source and the complicated treatments needed for seedling raising are major issues. This study explored the possibility of using compresseddecomposed rice straw and biochar from rice husk into a seedling-raising mat, to replace the soil and simplify the seeding process. A quadratic rotation-orthogonal combination experiment was conducted to investigate the effect of moisture content, pressure, and residence time on the formation of seedling-raising mat. The regression models between the compressing indicators and the process factors were established. The results showed that the following factors had significant effect on bending strength of the formed mat (P < 0.01): the pressure and residence time have extreme effects on dimensional stability (P < 0.01); but the influence of moisture content was insignificant (P > 0.05). The process parameters for compression were optimized and verified using Design-Expert software 8.0.6. The optimized parameters were moisture content of 33%, pressure of 23.0 MPa, and residence time of 61 s. The prediction error is less than 6% under this condition. The results may provide a reference for biomass seedling-raising mat compression. [ABSTRACT FROM AUTHOR]

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 RHBRRS 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. [ABSTRACT FROM AUTHOR]

The ant (Pheidole megacephala, Fabricius) has a unique and hard mandibular structure to cut branches and crush hard food. Inspired by this special geometric structure of the mandibular teeth, a stereoscopic microscope was used to view the image of the mandible of the ant. The Origin and AutoCAD software were used to obtain the outer profile of the mandibular teeth of the ant. The outer profile of the ant's mandibular teeth was fitted and expressed by fiveorder polynomial function. According to the analysis of the profile curve of the maxillary teeth, the fourth tooth is the most convex and the sharpest. The fourth tooth of the ant plays a key role in its feeding process, therefore, the structural parameters of the fourth maxillary tooth were selected as bionic elements for bionic blade design. To compare the cutting performance of the bionic and ordinary flat blades, the performance of bionic blade and the ordinary blade were conducted by using ANSYS software, the cutting force-deformation characteristics were tested using the Rapid TA practical texture analyser. The results of the element simulation showed that the mechanical properties of bionic blade were better than those of the ordinary blade. The results of the cutting experiments indicated that under the loading speed of 5 mm/s, the maximum cutting force of the bionic blade was 137.51 N, which is 12.17 % lower than that of the ordinary flat blade. The average cutting force of the bionic blade was 96.56 N, which is 11.58 % lower than that of the ordinary flat blade. The cutting energy consumption of the bionic blade was 9.68 J, which is 11.92 % lower than that of the ordinary flat blade. Under the loading speed of 10 mm/s, the maximum cutting force of the bionic blade was 143.88 N, which is 10.37 % lower than that of the ordinary flat blade. The average cutting force of the bionic blade was 101.03 N, which is 9.77 % lower than that of the ordinary flat blade. The cutting energy consumption of the bionic blade was 10.14 J, which is 9.95 % lower than that of the ordinary flat blade. The experimental results suggested that the bionic blade can effectively reduce the cutting force and energy consumption; thus, the bionic blade is more suitable for cutting stalks. These results will be helpful in the development of cutting elements for cutting and chopping of corn stover and other processing machinery. [ABSTRACT FROM AUTHOR]

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 slope is 40.2°. [ABSTRACT FROM AUTHOR]

At present, the quality of chopping stalks with the use of a corn combine harvester needs improvement. Therefore, this study aims at designing a hob-type stalk chopping device to be installed under the header which can realize multiple groups of parallel longitudinal arrangements. Moreover, the device will be able to cut and crush the root and the middle and upper parts of the stalks. The performance of a finite element analysis corroborated the satisfactory strength and stiffness of the designed chopping blade as the mechanical requirements. Moreover, the influencing working and structural parameters were determined using a theoretical analysis. Regarding the test factors, i.e., the tip angle of the blades, fixed angle and the rotational speed of chopper shaft, single-factor and central composite design tests were also performed. Furthermore, the percentage of the qualified length of chopped stalk and the power consumption of cutting stalk were taken as the evaluation indexes. Accordingly, the results revealed the influencing parameters to be ordered as the spindle speed > fixed angle > tip angle of the blades. Subsequently, the parameters were optimized using the response surface method. Based on the obtained results, the optimized parameters including the spindle speed, the fixed angle and the tip angle of the blades were specified as 1050 r/min, 56°, and 40°, respectively. The experimental validation was also carried out on the optimal combination of the parameters. The qualified lengths of the chopped stalks were found to be 92.9%, which were consistent with the predicted results of the model. Hence, the test results met the design requirements. [ABSTRACT FROM AUTHOR]