Biomimetic blades for soil-rototilling and stubble-breaking were designed learning from the geometrical structure of the tips of toes of mole rat （Scaptochirus moschatus）. The orientation, the number and the central...Biomimetic blades for soil-rototilling and stubble-breaking were designed learning from the geometrical structure of the tips of toes of mole rat （Scaptochirus moschatus）. The orientation, the number and the central angle of the biomimetic structure were taken as the testing factors. The optimal structure of the biomimetic blade was determined through the tests of soil-rototilling and stubble-breaking operation in an indoor soil bin. The optimal combination of the biomimetic structure pa- rameters is that three arc concave teeth are equally arranged on the front cutting edge with a central angle of 60°. The results of comparative tests between the optimal biomimetic blade and a conventional universal blade show the torque acting on the biomimetic blade is lower during soil-rototilling and stubble-breaking operations. The results of field tests show that the working quality of the biomimetic blades meets the requirements of the national standard of China. Tests of soil-rototilling show that, when the orientation of the biomimetic structure was at low and middle levels, the torque ofbiomimetic blades decreased from 34.17 N·m to 31.03 N·m. The torque also decreased with the increase of the number of biomimetic structure. The average torques were 34.57 N·m, 33.44 N·m and 31.37 N·m, respectively. The maximum different value between two levels of central angle was 0.41 N·m. Tests in field indicate that for soil-rototilling operation, the tillage depth is deeper than 80 mm, the soil-crushing rate （length of soil block less than 40 mm） is over 50 %, and the vegetation coverage rate is over 55 %. For stubble-breaking operation, the stubble-breaking depth is deeper than 70 ram, the stubble-breaking rate （length of stubble less than 40 mm） is over 60%, and the stubble coverage rate is over 80%, which can meet the stubble-breaking requirement of corn.展开更多
In order to address the low soil breaking rate,poor soil covering performance,and low working efficiency of the existing 3MT-1.8 and PMT-75 grapevine burying machines,two types of improved burying machines,namely the ...In order to address the low soil breaking rate,poor soil covering performance,and low working efficiency of the existing 3MT-1.8 and PMT-75 grapevine burying machines,two types of improved burying machines,namely the 3MTLJ-1.8 and 3MTXP-1.8,were developed in consideration of the local Ningxia soil conditions.Field experimental results indicated that the soil breaking rate of the 3MTLJ-1.8 machine was 71.44%,and its soil sampling volume increased by approximately 30%compared to that of the 3MT-1.8 machine.It was verified that the self-developed 3MTLJ-1.8 machine can be used in the southern regions of Ningxia.Furthermore,the soil sampling volume of the 3MTXP-1.8 burying machine was 0.24 m^(3)/m,and its soil breaking rate increased by more than 41.42%compared to the standard required volume.The 3MTXP-1.8 machine can be used in the northern areas of Ningxia,where the soil hardness is higher.The results can provide a reference for the development and popularization of grapevine burying machines in Ningxia.展开更多
Typically, soil samples must be crushed into particles for laboratory research. Thus, an efficient mechanism to ensure a uniform particle size is essential. We previously developed a rod mill device that performs well...Typically, soil samples must be crushed into particles for laboratory research. Thus, an efficient mechanism to ensure a uniform particle size is essential. We previously developed a rod mill device that performs well, but video analysis indicated that the shear forces applied by the rod were more effective than the compressive forces applied by the mill. The mechanism for this phenomenon is unclear. This study focused on clarifying the relationship between compressive load and abrasion when crushing dried and hardened soil particles. Soil pellets of the same size were prepared, and model experiments were performed, where vertical compression and abrasion were applied to the pellets until they fractured. The results showed that soil pellets were fractured easily when an abrasive load was continuously applied in the circumferential direction. Additionally, the load required to fracture the soil pellets was much lower than the required vertical compressive load. The rod mill device was previously thought to fracture soil aggregates by gradually stripping soil particles away from the surface. However, our experimental results clarified that the fracture process started at the center and subsequently induced the entire pellet’s sudden failure.展开更多
The bank slopes in hydro-fluctuation areas of reservoirs or lakes suffer from severe erosion due to an absence of protection. Waves are one of the important external forces that cause bank erosion and slope failures. ...The bank slopes in hydro-fluctuation areas of reservoirs or lakes suffer from severe erosion due to an absence of protection. Waves are one of the important external forces that cause bank erosion and slope failures. However, the processes and quantified impacts of wave-induced erosion on slopes remain unclear under different water level-fluctuation conditions. This paper focuses on the characteristics of wave-induced slope erosion under three conditions: water level dropping(WLD), fixed(WLF) and rising(WLR). A steel tank with glass pane was used to simulate the wave-induced slope erosion in the three treatments. The slope elevation data were collected by using the method of the pin meter for every 15 minutes from the beginning to the end, a total of 5 times during all treatments. These data were processed by using software(SURFER 9.0) to get the slope micro-topography and the erosion volume. Then the temporal and spatial change of slope erosion was analysed according to the erosion amount or erosion rate calculated based on bulk density of slope soil. The results demonstrated that the soil erosion rates for different water level changing treatments are in the following order: WLR>WLD>WLF. For the erosion spatial variation, the middle part of the slope was the major source of sediment in the WLD. The upper part of the slope was the major source of the sediment for the other two treatments. Compared with the standard deviation(SD), the coefficient of variation(CV) based on the SD is more representative of variations in the soil surface roughness(SSR). Furthermore, the good fit between the SSR and soil erosion rate have the potential to be used to predict soil erosion. Above all, the injection angle of the wave determined the rate of erosion to some extent, and the fall-back flow of the wave could also influence the extent of erosion, deposition, and bank morphology. It is vital to choose the appropriate index(SD or CV) in the three water levels to improve the prediction accuracy. This paper could provide scientifi展开更多
为获取适用于海南热区砖红壤与触土部件相互作用的离散元仿真模型参数,该文利用EDEM仿真软件中Hertz-Mindlin with JKR接触模型对海南地区砖红壤进行相关模型参数标定,首先以含水率为7.8%、实际休止角为32.35°的砖红壤为研究对象,...为获取适用于海南热区砖红壤与触土部件相互作用的离散元仿真模型参数,该文利用EDEM仿真软件中Hertz-Mindlin with JKR接触模型对海南地区砖红壤进行相关模型参数标定,首先以含水率为7.8%、实际休止角为32.35°的砖红壤为研究对象,以物理试验获取的砖红壤-砖红壤、砖红壤-触土部件间恢复系数、静摩擦系数及滚动摩擦系数为标定对象,应用Plackett-Burman设计试验筛选出对休止角有显著影响的参数:即砖红壤-砖红壤滚动摩擦系数、JKR表面能、砖红壤-28MnB5板滚动摩擦系数、砖红壤-砖红壤恢复系数。进一步以砖红壤颗粒休止角为响应值,基于Box-Behnken设计试验得到休止角与显著性参数的二阶回归模型,并以实际休止角为目标,针对显著性参数进行寻优,得到最佳组合:砖红壤-砖红壤滚动摩擦系数为0.07、砖红壤-28MnB5板滚动摩擦系数为0.24、砖红壤-砖红壤恢复系数为0.4、JKR表面能为4.31J/m^2。最后在标定的参数下进行休止角与破土阻力离散元仿真验证试验,对比计算得出仿真休止角与实测休止角相对误差为0.62%,仿真破土阻力与实测破土阻力相对误差为3.43%,并通过对比分析两次试验中破土阻力变化曲线的拟合情况,得出两曲线间的可决系数R2=0.993 9,均方根误差RMSE=0.017 7,该结果表明标定所得相关参数可用作海南热区砖红壤离散元仿真。展开更多
基金This work was supported by the National Natural Science Foundation of China （Grant No. 51475204, 51105161）, the National Agricultural Technology Transformation Foundation of China （Grant No. 2013GB23600661）, the Natural Science Foundation of Hubei Province of China （Grant No. 2011CDB 149）, the Fundamental Research Funds for the Central Universities （Grant No. 2011QC009）, the Startup Foundation for Doctors of Huazhong Agricultural University （Grant No. 2010BQ009）, and the ＂National 985 Project＂ in Jilin University, China.
文摘Biomimetic blades for soil-rototilling and stubble-breaking were designed learning from the geometrical structure of the tips of toes of mole rat （Scaptochirus moschatus）. The orientation, the number and the central angle of the biomimetic structure were taken as the testing factors. The optimal structure of the biomimetic blade was determined through the tests of soil-rototilling and stubble-breaking operation in an indoor soil bin. The optimal combination of the biomimetic structure pa- rameters is that three arc concave teeth are equally arranged on the front cutting edge with a central angle of 60°. The results of comparative tests between the optimal biomimetic blade and a conventional universal blade show the torque acting on the biomimetic blade is lower during soil-rototilling and stubble-breaking operations. The results of field tests show that the working quality of the biomimetic blades meets the requirements of the national standard of China. Tests of soil-rototilling show that, when the orientation of the biomimetic structure was at low and middle levels, the torque ofbiomimetic blades decreased from 34.17 N·m to 31.03 N·m. The torque also decreased with the increase of the number of biomimetic structure. The average torques were 34.57 N·m, 33.44 N·m and 31.37 N·m, respectively. The maximum different value between two levels of central angle was 0.41 N·m. Tests in field indicate that for soil-rototilling operation, the tillage depth is deeper than 80 mm, the soil-crushing rate （length of soil block less than 40 mm） is over 50 %, and the vegetation coverage rate is over 55 %. For stubble-breaking operation, the stubble-breaking depth is deeper than 70 ram, the stubble-breaking rate （length of stubble less than 40 mm） is over 60%, and the stubble coverage rate is over 80%, which can meet the stubble-breaking requirement of corn.
基金supported by the Ningxia Hui Autonomous Region Science and Technology Support Plan Project,2015BY11102.
文摘In order to address the low soil breaking rate,poor soil covering performance,and low working efficiency of the existing 3MT-1.8 and PMT-75 grapevine burying machines,two types of improved burying machines,namely the 3MTLJ-1.8 and 3MTXP-1.8,were developed in consideration of the local Ningxia soil conditions.Field experimental results indicated that the soil breaking rate of the 3MTLJ-1.8 machine was 71.44%,and its soil sampling volume increased by approximately 30%compared to that of the 3MT-1.8 machine.It was verified that the self-developed 3MTLJ-1.8 machine can be used in the southern regions of Ningxia.Furthermore,the soil sampling volume of the 3MTXP-1.8 burying machine was 0.24 m^(3)/m,and its soil breaking rate increased by more than 41.42%compared to the standard required volume.The 3MTXP-1.8 machine can be used in the northern areas of Ningxia,where the soil hardness is higher.The results can provide a reference for the development and popularization of grapevine burying machines in Ningxia.
文摘Typically, soil samples must be crushed into particles for laboratory research. Thus, an efficient mechanism to ensure a uniform particle size is essential. We previously developed a rod mill device that performs well, but video analysis indicated that the shear forces applied by the rod were more effective than the compressive forces applied by the mill. The mechanism for this phenomenon is unclear. This study focused on clarifying the relationship between compressive load and abrasion when crushing dried and hardened soil particles. Soil pellets of the same size were prepared, and model experiments were performed, where vertical compression and abrasion were applied to the pellets until they fractured. The results showed that soil pellets were fractured easily when an abrasive load was continuously applied in the circumferential direction. Additionally, the load required to fracture the soil pellets was much lower than the required vertical compressive load. The rod mill device was previously thought to fracture soil aggregates by gradually stripping soil particles away from the surface. However, our experimental results clarified that the fracture process started at the center and subsequently induced the entire pellet’s sudden failure.
基金National Natural Science Foundation of China(Grant No.41761144060)the Innovative Talents Promotion Plan in Shaanxi Province(Grant No.2017KJXX-83).
文摘The bank slopes in hydro-fluctuation areas of reservoirs or lakes suffer from severe erosion due to an absence of protection. Waves are one of the important external forces that cause bank erosion and slope failures. However, the processes and quantified impacts of wave-induced erosion on slopes remain unclear under different water level-fluctuation conditions. This paper focuses on the characteristics of wave-induced slope erosion under three conditions: water level dropping(WLD), fixed(WLF) and rising(WLR). A steel tank with glass pane was used to simulate the wave-induced slope erosion in the three treatments. The slope elevation data were collected by using the method of the pin meter for every 15 minutes from the beginning to the end, a total of 5 times during all treatments. These data were processed by using software(SURFER 9.0) to get the slope micro-topography and the erosion volume. Then the temporal and spatial change of slope erosion was analysed according to the erosion amount or erosion rate calculated based on bulk density of slope soil. The results demonstrated that the soil erosion rates for different water level changing treatments are in the following order: WLR>WLD>WLF. For the erosion spatial variation, the middle part of the slope was the major source of sediment in the WLD. The upper part of the slope was the major source of the sediment for the other two treatments. Compared with the standard deviation(SD), the coefficient of variation(CV) based on the SD is more representative of variations in the soil surface roughness(SSR). Furthermore, the good fit between the SSR and soil erosion rate have the potential to be used to predict soil erosion. Above all, the injection angle of the wave determined the rate of erosion to some extent, and the fall-back flow of the wave could also influence the extent of erosion, deposition, and bank morphology. It is vital to choose the appropriate index(SD or CV) in the three water levels to improve the prediction accuracy. This paper could provide scientifi
文摘为获取适用于海南热区砖红壤与触土部件相互作用的离散元仿真模型参数,该文利用EDEM仿真软件中Hertz-Mindlin with JKR接触模型对海南地区砖红壤进行相关模型参数标定,首先以含水率为7.8%、实际休止角为32.35°的砖红壤为研究对象,以物理试验获取的砖红壤-砖红壤、砖红壤-触土部件间恢复系数、静摩擦系数及滚动摩擦系数为标定对象,应用Plackett-Burman设计试验筛选出对休止角有显著影响的参数:即砖红壤-砖红壤滚动摩擦系数、JKR表面能、砖红壤-28MnB5板滚动摩擦系数、砖红壤-砖红壤恢复系数。进一步以砖红壤颗粒休止角为响应值,基于Box-Behnken设计试验得到休止角与显著性参数的二阶回归模型,并以实际休止角为目标,针对显著性参数进行寻优,得到最佳组合:砖红壤-砖红壤滚动摩擦系数为0.07、砖红壤-28MnB5板滚动摩擦系数为0.24、砖红壤-砖红壤恢复系数为0.4、JKR表面能为4.31J/m^2。最后在标定的参数下进行休止角与破土阻力离散元仿真验证试验,对比计算得出仿真休止角与实测休止角相对误差为0.62%,仿真破土阻力与实测破土阻力相对误差为3.43%,并通过对比分析两次试验中破土阻力变化曲线的拟合情况,得出两曲线间的可决系数R2=0.993 9,均方根误差RMSE=0.017 7,该结果表明标定所得相关参数可用作海南热区砖红壤离散元仿真。
