ass日本风韵熟妇pics男人扒开女人屁屁桶到爽|扒开胸露出奶头亲吻视频|邻居少妇的诱惑|人人妻在线播放|日日摸夜夜摸狠狠摸婷婷|制服 丝袜 人妻|激情熟妇中文字幕|看黄色欧美特一级|日本av人妻系列|高潮对白av,丰满岳妇乱熟妇之荡,日本丰满熟妇乱又伦,日韩欧美一区二区三区在线

To solve the problems of poor land leveling and nonuniform axial distribution of soil in rotary tillage after opening drainage ditching in the middle and lower reaches of the Yangtze River, a blade roller for rotary tillage and axial land leveling with gradual spiral angle was designed. The volume parameter equation of soil disturbance of rotary tillage blade roller was established, the mechanical conditions of axial soil transport of rotary tillage blade were analyzed, and the spiral line equation of rotary tillage blade arrangement with gradient spiral angle was established. The key factors affecting the axial uniformity of soil layer were determined as blade roller rotary speed, cutting pitch of rotary tillage and initial spiral angle. The discrete element simulation model of rotary tillage blade roller with gradual spiral angle was established by using distinct element method. The regression equation of soil layer levelness was established by orthogonal test with the blade roller rotary speed, cutting pitch of rotary tillage and initial spiral angle as the test parameters. The Design-Expert analysis software was used, when the blade roller rotary speed, cutting pitch of rotary tillage and initial spiral angle were 260r/min, 8.3cm, and 71°, respectively, the optimized soil layer levelness was 17.35mm. The field test under the optimized parameters showed that the soil layer levelness, soil distribution uniformity, tillage depth stability and soil broken rate were 14.5mm, 8.82%, 92.34% and 81.66%, respectively, and the comprehensive tillage performance was better than that of the traditional rotary tillage blade roller. The research result could provide a reference for the equipment optimization and upgrading of the combined operation of wheat planting, drainage ditching and rotary tillage in agricultural areas of the middle and lower reaches of the Yangtze River.