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The purpose of this research was to study heat and moisture retention and breaking force properties of different plastic mulches. The field experiments with different plastic mulches were carried. The results showed that, the fracture strength and the right-angle tear strength of reinforced mulch are superior to those of weather-resistant mulch and ordinary mulch. The soil moisture, humidity and daily mean temperature under plastic mulches were affected by the laying time at a 1% probability level. It was also found that the variety had no significant effect on daily mean temperature under plastic mulches. A strong correlation was found between breaking force and the laying time of plastic film. A multiple linear regression model was developed to determine the relationship between the heat and moisture retention properties and breaking force. The R2 values of three plastic mulch varieties regression model were 0.904, 0.913 and 0.931. The breaking force of reinforced mulch and weather-resistant mulch indicates that plastic mulch recovery should be conducted after autumn, before it is too weakened by exposure.

In China, especially in Xinjiang, the plastic mulch remaining in the soil has seriously jeopardized the safety of soil resources. According to the survey of the Agriculture Department of Xinjiang Autonomous Region, the average weight of residual film in the cultivated layer of cotton planted in Xinjiang has reached 269 kg/ hm^2, equivalent to 36,900m2/ hm^2, and the residual film pollution problems in Gansu, Inner Mongolia and Ningxia provinces are also prominent. In order to solve the problem of pollution of residual film in plowed soil, this paper designed a rotary nail tooth plastic mulch recycling machine. The machine mainly composed of nail tooth, nail-toothed roller, brush roller, conveying device, and transmission system. This paper mainly designed the structural parameters and working parameters of nail tooth, nail-toothed roller, brush roller and conveying device. Finally, through single factor test in field, the law of influence of nail tooth angle, nail roller‘s rotation speed, forward speed and depth of inserting soil on the recovery rate is obtained, and when the nail tooth angle is 90°, the nail tooth rotation speed is 120r/min, when the depth of the soil is 100mm, the forward speed is 4km, the recovery efficiency of the recycling machine can meet the working requirements.

This paper analyzes the influence of methanol-containing diesel at the accelerating condition on the performance of diesel engine. The more the methanol is, the greater the changes of pΔt and σΔt , and the worse the dynamic performance is. At the same time the soot emission increases, which mainly generates at the initial stage of fuel acceleration. The emission of NOx goes up after dropping, then slightly decreases and tends to be stable.

In this paper, a novel 5UPS-RPS 5-dof parallel mechanism with five UPS-type active legs and one RPS-type constraint leg is proposed, and its kinematics and statics are studied systematically. First, a prototype of this PM is constructed and the dof of this PM is analyzed. Second, analytic formulas for solving the inverse displacement kinematics are derived. Third, the velocity Jacobian matrix and Hessian matrix are derived and analytic formulas for solving the velocities and accelerations of this PM are derived systematically. Finally, an analytic example is given for solving the length, velocity and acceleration of the active legs.

At present, collectors for potato film residues in China are mainly used to pick up film residues after the harvest of potatoes, during which the pick-up rate of film residues and the work efficiency are low. Aiming at the above problems, a belt-tooth type collector for potato film residues installed on 4UM-1000 potato harvester was designed. It is mainly composed of a film picking device, a film transport device, a film collecting device and an installation frame. It can realize the harvest of potatoes and pick-up of film residues at the same time. The pick-up rate of film residues and potato damage rate are taken as response indicators. Through single factor test, the optimal combination of structural parameters of film picking teeth was obtained as below: the number in the horizontal direction is 4, the longitudinal space is 300mm, the length is 130mm, and picking teeth are arranged in a non-staggered way. Experiments were designed by using the response surface methodology (RSM). The optimal working parameters of the machine are determined as below: the forward speed is 2.66km/h, the rotation speed of the driving shaft is 89.63r/min and the rotation speed of the conveyor chain shaft is 184.17r/min. Field experiments were carried out to verify the above results, where the verified pick-up rate of film residues and potato damage rate were 90.29% and 4.72% respectively, both of which met design requirements of technical specifications.

To ensure the variation of tooth backlash in allowable value required in common gears transmission, a new transmission mechanism was proposed in this paper to solve the problem of tooth backlash change, composed by an eccentric gear and an eccentric modified gear. The design principle of the eccentric gears was described in this paper. According to the involutes tooth profile generating principle, the tooth profile data was obtained. The eccentric modified gears were manufactured through powder metallurgy, and were successfully applied to the planetary transplanting mechanism, passing the field testing. Key words-Eccentric modified gear,Modified gear ,Backlash, Rice planetary transplanting mechanism