Search

To address the low clearance rate issue of the anti-blocking mechanism for maize no-till planters in the Huang-Huai-Hai Plain of China, experiments and simulations were conducted to analyze the individual and collective movements of straw under the action of the round roller-claw anti-blocking mechanism. A tracer-based measurement method for straw displacement was applied firstly. Experimental results showed that the straw forward displacement could be characterized by the average horizontal displacements of longitudinal and lateral tracers, while the straw side displacement could be characterized by the lateral displacement of the longitudinal tracer. The straw forward displacement was 58.95% greater than the side displacement. Forward, side, and total displacements of straw increased as the mechanism's forward speed increased from 3 km/h to 7 km/h, with corresponding rates of increase at 233.98%, 43.20%, and 162.47%, respectively. Furthermore, a model of straw–soil–mechanism interaction was constructed in EDEM 2022 software. The relative error between experimental and simulated straw clearance rates was 11.20%, confirming the applicability of the simulation model for studying straw–soil–mechanism interaction. Based on the simulation model, three straw tracers of different lengths were selected to study the motion behavior of straw. It was inferred that despite differences in straw length, the movement behaviors of the three straw tracers under the influence of the anti-blocking mechanism were similar. Additionally, longer straws exhibited greater displacements in all directions. This paper serves as a reference for studying straw motion behavior influenced by anti-blocking mechanisms. [ABSTRACT FROM AUTHOR]

Mechanical-chemical synergy has been proven efficient in weed control. However, characterizing the state of the weed–soil complex after mechanical weeding and revealing its effects on subsequent herbicide application is still challenging, which restricts the implementation of this technology. This paper first presents a method to characterize the state of the weed–soil complex from the perspectives of the fragmentation and composite characteristics. The regrowth of the weed–soil complex and the effects of complemented herbicide-reduced spraying on weed control efficacy and crop yield were then investigated. The results showed that the typical diameters of the weed–soil complexes were 10.67 cm and 2.82 cm after inter-row hoe shovel and intra-row finger weeding, respectively. There were mainly two and four weed–soil complex states after inter-row and intra-row weeding, respectively. The regrowth rate corresponding to the weed–soil complex state with the largest component proportion after inter-row and intra-row weeding was 76.91% and 18.37%, respectively. The additional chemical herbicide sprayed on the weed–soil complex significantly improved the fresh weight control efficacy of 95.12% for the preposed inter-row mechanical weeding and 138.07% for the preposed intra-row mechanical weeding in the maize silking stage. The maize yield of inter-row mechanical–75% chemical application treatment was 9.27% higher than that of chemical treatment. Mechanical weeding creates a suitable weed–soil complex state for subsequent chemical application and improves the synergistic weeding effect. [ABSTRACT FROM AUTHOR]

The heat-transfer characteristics of 128 small-sized plate-fin heat sinks in a supercomputer chassis are investigated with CFD simulation. The V-shaped curves of the chip temperature versus fin pitch and fin thickness are derived and a thermal resistance model is built to explore the profile and obtain the convective heat-transfer coefficient of the heat sinks. It turns out that the V-shaped profile arises from the joint action of the thermal conduction and convection of heat sink, which can be attributed to the intricacy of the dependencies of thermal resistances on either fin pitch or thickness. It can be further concluded that Biot criterion is applicable to estimate the Biot number of large-scale plate-fin heat sink but not applicable for the small-sized one. The convective heat-transfer coefficient is a complicated function of fin pitch and fin thickness. The empirical formulas of heat transfer are obtained and the fin pitch and fin thickness are optimized. [DOI: 10.1.115/1.2804102] Keywords: plate-fin heat sink array, heat transfer, thermal resistance model, empirical design rule, revised Biot criterion