According to the characteristics of compacted snow-ice, the formation types and microstructure of compacted snow-ice were analyzed to know the snow clearing performance and rule and laid the theoretical foundation for related design of snow clearing equipment. In addition, the microscopic snow clearing performance, physical and mechanical properties were described and further research was proposed, which have provided a scientific basis for technology research and equipment development in the field of snow clearing.
As for the crops root stubble having the developed root system, the digging shovel with drag reduction has been designed for reducing disturbance to soil generated by soil-engaging components and decreasing power consumption. Drag reduction performance test of the offset mining shovels is developed with the method of orthogonal rotation combination test design, law and importance degree of the four critical factors’ influence on traction resistance has been found, including shovel buried angle, slip cutaway, buried depth, and machine forward speed. Then the mathematical model of traction resistance is developed and the optimum parameters for digging shovel resistance are received.
The microscopic deformation mechanism was taken into account to research the high efficient solid ice and snow clearing technology. The solid ice and snow constitutive model was established, which the deformation mechanism of snow microstructure and macroscopic continuous behavior were linked together, considering the damage of solid ice and snow depends on the mechanical properties of the snow volume elements of the grain bonds between grains, and using the microstructure factor scale the stress state of microstructure in the continuous stress. The density is 520Kg/m3-600Kg/m3 of the solid ice and snow was selected for studying and the homogeneous triaxial loading test was conducted by using the SJ-1A strain control type triaxial shear instrument. The relations of local strain rate with limit stress was established according to the simulation analysis conducted the constitutive model that was been established, the results found that both of those showed a near-linear relations, it was fit with the experience relations. The computer simulation and experimental curves deviated a little, and the reasonableness of the established solid ice and snow constitutive model was verified. Studied have shown that the failure rule of solid ice and snow can be well described by the constitutive model, which presents a theoretical reference for the design of key icebreaking components.
According to the operator experiences, the variable rate fertilization system based on the fuzzy self-tuning PID controller is researched in this paper, which is driven by electrically and hydraulic system. This system solves the problem that the parameters adjustment of the traditional PID is difficult. The system model is presented and is simulated by using MATLAB/ SIMULINK toolbox. The simulation results shows that the fuzzy self-tuning PID control could obtain better dynamic response and achieve the expected control effects. In order to verify this control system performance, many experiments are carried on in the lab. The experiments results show that the variable rate fertilization system based on fuzzy self-tuning PID control has high control accuracy and could meet the control requirements of the variable rate fertilization in precision agriculture.
The traction characteristics of lubricant is one of the important parameters of the dynamic performance of bearings design .This paper chose three significant factors affecting the traction coefficient:temperature、load and rotate speed. Test results showed that the traction coefficient under the high load is significantly higher than under low load from room temperature to 135 °C. After more than 135 °C, the traction coefficient under the low load is higher than under the high load. It illustrated that the grease was sensitive to temperature but it reflected high temperature stable performance.The optimum conditions were obtained by Design-Expert software optimization : temperature for 235°C、load for 2800.00N、rotate speed for 183.17r/min and in this time the traction coefficient is at 0.547 in this test. It shown that the grease fitted the low speed and heavy load equipment.
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