The emergence rate and vitality of maize are directly affected by the sowing depth,and the uniformity of this depth is an important performance indicator of a planter,while the effective soil surface height informatio...The emergence rate and vitality of maize are directly affected by the sowing depth,and the uniformity of this depth is an important performance indicator of a planter,while the effective soil surface height information acquisition is the prerequisite for ensuring the accuracy of sowing depth control.The soil surface height variation acquisition system of a precision corn planter often produces profiling errors when performing active profiling due to interference from ground debris.In this study,a multipoint soil surface height variation information acquisition system was investigated,which consists of a ranging sensor group and a microcontroller unit(MCU)using a data comparison and screening method.The structure and specifications of the ranging sensors were determined according to the soil surface height variation and debris size,and a nonessential profiling control program was developed.Performed tests on the information acquisition system indicated that the measurement accuracy of the system was 3 mm,and when advancing at a speed of 8 km/h,the accuracy of the profiling decision and the system stability were 97.1%and 94.1%,respectively,indicating that the system was capable of nonessential profile control.The designed ranging system could provide a reference for the design of a ground information acquisition system of precision planters with an active profiling mechanism.展开更多
Existing sugarcane planters are difficult to have ideal seeding trajectory and motion attitude at the same time, and the speed is difficult to meet the requirements at the critical stage, resulting in poor stability, ...Existing sugarcane planters are difficult to have ideal seeding trajectory and motion attitude at the same time, and the speed is difficult to meet the requirements at the critical stage, resulting in poor stability, which ultimately makes it impossible to ensure that the sugarcane seeding is carried out in accordance with the agronomic requirements to ensure that the cane buds are oriented toward the wall of the seeding trench. Aiming at the second-order non-circular planetary gear system pendulum seeding mechanism of the planter, the paper innovatively adopts the combination of inverse design and multi-objective layered accurate optimization to solve the problems of attitude, speed and trajectory that do not meet the requirements of fixed-attitude seeding that still exists in the process of sugarcane seeding. The second-order non-circular planetary gear system is simplified into a three-rod two-degree-of-freedom mechanism, and the radius of the pitch curve of each non-circular gear is solved inversely by actively preplanning the static trajectory of the cane seed motion and analyzing the law of motion of the rod assembly. Determining the range of cane seed attitude angles in different motion phases as the first layer optimization objective, and fine-tuning the position of static trajectory key type value points to achieve the first layer optimization. Based on the non-circular gear pitch curve obtained from optimization, the interpolation points are marked on each non-circular gear pitch curve of the second-order non-circular planetary gear system, and based on the parameter optimization method of human-computer interaction, the radius values corresponding to the interpolation points of the non-circular gear pitch curve are fine-tuned to optimize the pitch curves, so as to satisfy the speed requirements of the cane species in each stage, and at the same time to make the convexity of non-circular gears in line with the principle of gear mesh, so as to complete the second layer of accurate optimization. The resul展开更多
A detailed 3-D hail cloud numerical model and parameterization of mierophysieal processes were described in Part Ⅰ(Hong 1999)of this study.In this part,a hail cloud occurring in Xunyi area.Shaanxi Province on July 8,...A detailed 3-D hail cloud numerical model and parameterization of mierophysieal processes were described in Part Ⅰ(Hong 1999)of this study.In this part,a hail cloud occurring in Xunyi area.Shaanxi Province on July 8,1997 is simulated by the model to analyze mechanisms of hail formation and hail suppression with seeding.The results show that 97% of hail embryos are frozen drops.The seeding experiments with AgI in terms of heights show that if the seeding is made before hail formation,the optimum seeding position is located in the maximum updraft area and its center,i.e.,AgI is seeded in the zone with high water content to be coordinated with maximum zone of the updraft.The seeding makes concentrations of graupel and frozen drop increase and their average mass or size decrease,so that the proportion of conversion from graupel and frozen drop into hail descends greatly,and the mass and concentration of hailstone are decreased to achieve our purpose for hail suppression.展开更多
基金This study was financially supported by the Special Funding Project for Public Welfare Industries(Agriculture)Scientific Research:Research on Mechanized Cultivation Model in Maize Planting Area of State Farm(201503116-04-04)and conducted in the Conservation Tillage Technology Center of the Heilongjiang Provincial Education Department jointly established by both corporations and universities.
文摘The emergence rate and vitality of maize are directly affected by the sowing depth,and the uniformity of this depth is an important performance indicator of a planter,while the effective soil surface height information acquisition is the prerequisite for ensuring the accuracy of sowing depth control.The soil surface height variation acquisition system of a precision corn planter often produces profiling errors when performing active profiling due to interference from ground debris.In this study,a multipoint soil surface height variation information acquisition system was investigated,which consists of a ranging sensor group and a microcontroller unit(MCU)using a data comparison and screening method.The structure and specifications of the ranging sensors were determined according to the soil surface height variation and debris size,and a nonessential profiling control program was developed.Performed tests on the information acquisition system indicated that the measurement accuracy of the system was 3 mm,and when advancing at a speed of 8 km/h,the accuracy of the profiling decision and the system stability were 97.1%and 94.1%,respectively,indicating that the system was capable of nonessential profile control.The designed ranging system could provide a reference for the design of a ground information acquisition system of precision planters with an active profiling mechanism.
基金supported by The National Natural Science Foundation of China (Grant No.52265028)Guangxi Natural Science Foundation of China (Grant No.2021JJA160046).
文摘Existing sugarcane planters are difficult to have ideal seeding trajectory and motion attitude at the same time, and the speed is difficult to meet the requirements at the critical stage, resulting in poor stability, which ultimately makes it impossible to ensure that the sugarcane seeding is carried out in accordance with the agronomic requirements to ensure that the cane buds are oriented toward the wall of the seeding trench. Aiming at the second-order non-circular planetary gear system pendulum seeding mechanism of the planter, the paper innovatively adopts the combination of inverse design and multi-objective layered accurate optimization to solve the problems of attitude, speed and trajectory that do not meet the requirements of fixed-attitude seeding that still exists in the process of sugarcane seeding. The second-order non-circular planetary gear system is simplified into a three-rod two-degree-of-freedom mechanism, and the radius of the pitch curve of each non-circular gear is solved inversely by actively preplanning the static trajectory of the cane seed motion and analyzing the law of motion of the rod assembly. Determining the range of cane seed attitude angles in different motion phases as the first layer optimization objective, and fine-tuning the position of static trajectory key type value points to achieve the first layer optimization. Based on the non-circular gear pitch curve obtained from optimization, the interpolation points are marked on each non-circular gear pitch curve of the second-order non-circular planetary gear system, and based on the parameter optimization method of human-computer interaction, the radius values corresponding to the interpolation points of the non-circular gear pitch curve are fine-tuned to optimize the pitch curves, so as to satisfy the speed requirements of the cane species in each stage, and at the same time to make the convexity of non-circular gears in line with the principle of gear mesh, so as to complete the second layer of accurate optimization. The resul
文摘A detailed 3-D hail cloud numerical model and parameterization of mierophysieal processes were described in Part Ⅰ(Hong 1999)of this study.In this part,a hail cloud occurring in Xunyi area.Shaanxi Province on July 8,1997 is simulated by the model to analyze mechanisms of hail formation and hail suppression with seeding.The results show that 97% of hail embryos are frozen drops.The seeding experiments with AgI in terms of heights show that if the seeding is made before hail formation,the optimum seeding position is located in the maximum updraft area and its center,i.e.,AgI is seeded in the zone with high water content to be coordinated with maximum zone of the updraft.The seeding makes concentrations of graupel and frozen drop increase and their average mass or size decrease,so that the proportion of conversion from graupel and frozen drop into hail descends greatly,and the mass and concentration of hailstone are decreased to achieve our purpose for hail suppression.