The current automatic scallion-transplanting machine is a complicated mechanism composed of two linkage mechanisms and two band carriers.It delivers seedlings ine ciently because of the movement limitations of the lin...The current automatic scallion-transplanting machine is a complicated mechanism composed of two linkage mechanisms and two band carriers.It delivers seedlings ine ciently because of the movement limitations of the linkage mechanism.This paper proposes a new high-order non-circular gear train for an automatic scallion-seedling feeding mechanism.The proposed gear train has an asymmetrical transmission ratio;i.e.,its transmission ratio varies.This allows the mechanism’s execution component to move in a long displacement and rotate in a large rotation angle.The long displacement enables the execution component to reach the designed working position,and the large rotation angle allows it to feed a scallion in the required pose.A mathematical model for calculating the asymmetrical transmission ratio was established according to the closure requirements and the full-cycle motion of the driven gear pitch curve.Then,the parameter-design model of the new seedling-feeding mechanism was established,based on precise pose points and trajectory-shape control points.Moreover,an aided-design program was developed to obtain the parameter-solution domain of the scallion-seedling feeding mechanism.The mechanism parameters,which met the seedling-feeding function,were optimized to determine the transmission ratio,using a program and a kinematic simulation.Finally,a prototype of the mechanism was produced,and a seedling-feeding experiment was carried out.One-thousand seedlings were tested at a rate of 100 seedlings per minute,and the statistical success rate was 93.4%.Thus,the automatic scallion-seedling feeding mechanism significantly improves the e ciency of automatically transplanting scallions.展开更多
[Objectives] This study was conducted to explore the dissipation dynamics of chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile) in scallion.[Methods] The level of residue and the dissipation of chlorothalonil and...[Objectives] This study was conducted to explore the dissipation dynamics of chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile) in scallion.[Methods] The level of residue and the dissipation of chlorothalonil and its main metabolite 4-hydroxy-2,5,6-trichloroisophthalonitrile in scallion in Beijing and Jiangsu experimental bases were determined via acetonitrile extraction and ultra-performance liquid chromatography coupled with ultraviolet detection (UPLC-UV).[Results] The dissipation of chlorothalonil in scallion followed the first-order kinetic model and the half-life of chlorothalonil in scallion was 3.5-4.1 d. The final residue of chlorothalonil in scallion decreased over time after the last application. After chlorothalonil was applied at 1 050 or 1 575 g a.i./hm 2 3 or 4 times, the maximum residue level of chlorothalonil was 1.48, 1.21, 0.72 and 0.45 mg/kg 5, 7, 10 and 14 d after the last application, while that of its 4-hydroxy metabolite was 0.25, 0.19, 0.13 and 0.09 mg/kg, respectively.[Conclusions] The results may provide experimental evidence for evaluating the safety of the use of chlorothalonil in scallion.展开更多
[Objectives] The aim was to reveal the distribution of soil organic matter content in cultivated land in the Se-rich areas of Hainan in 1980and 2010, so as to provide reference for the study on the evolution of soil o...[Objectives] The aim was to reveal the distribution of soil organic matter content in cultivated land in the Se-rich areas of Hainan in 1980and 2010, so as to provide reference for the study on the evolution of soil organic matter content.[Methods] With the combination of field investigation with indoor analysis, the characteristics of organic matter content in the Se-rich areas of Hainan in 1980 and 2010 was revealed by means of spatial analysis, and the differences were analyzed.[Results] In the last 30 years, the proportion of 20-30 g/kg of soil organic matter content in the Se-rich areas of Hainan was reduced, but the content of soil organic matter in the area generally increased. The average value of the content of organic matter in the area was increased from 25.3 g/kg in the 1980s to 28.1 g/kg, but its spatial distribution was uneven.[Conclusions] The farmers should be guided to change the fertilization structure, and attention should be paid to the application of organic fertilizer, so as to improve the soil organic matter content.展开更多
Se is one of trace elements necessary for the human body,and human body could absorb Se via the food. Se intake is insufficient in 2/3 region of China,which seriously affects health of local residents. Therefore,the r...Se is one of trace elements necessary for the human body,and human body could absorb Se via the food. Se intake is insufficient in 2/3 region of China,which seriously affects health of local residents. Therefore,the research of Se-rich fertilizer and the development of Se-rich product become the research focus in food science,medicine and other fields. There are rich marine resources in Beibu Gulf waters of Guangxi,and much carapace organic waste is generated. These carapace waste not only has high Se content but also is composed of a lot of Ca. The preparation of Se-rich & high-Ca fertilizer by these carapace waste not only reaches the target of recycling and environment friendly but also increases the yield of agricultural products,reduces diseases and pests,improves quality,increases the added value of agricultural product,which brings better economic benefit and meets people's demand for healthy food.展开更多
基金Supported by the National Key Research and Development Program of China(Grant No.2017YFD0700800)National Natural Science Foundation of China(Grant Nos.51775512,51975536)+1 种基金Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ20E050003)Basic Public Welfare Technology Application Research Projects of Zhejiang Province(Grant Nos.LGN19E050002,LGN20E050006).
文摘The current automatic scallion-transplanting machine is a complicated mechanism composed of two linkage mechanisms and two band carriers.It delivers seedlings ine ciently because of the movement limitations of the linkage mechanism.This paper proposes a new high-order non-circular gear train for an automatic scallion-seedling feeding mechanism.The proposed gear train has an asymmetrical transmission ratio;i.e.,its transmission ratio varies.This allows the mechanism’s execution component to move in a long displacement and rotate in a large rotation angle.The long displacement enables the execution component to reach the designed working position,and the large rotation angle allows it to feed a scallion in the required pose.A mathematical model for calculating the asymmetrical transmission ratio was established according to the closure requirements and the full-cycle motion of the driven gear pitch curve.Then,the parameter-design model of the new seedling-feeding mechanism was established,based on precise pose points and trajectory-shape control points.Moreover,an aided-design program was developed to obtain the parameter-solution domain of the scallion-seedling feeding mechanism.The mechanism parameters,which met the seedling-feeding function,were optimized to determine the transmission ratio,using a program and a kinematic simulation.Finally,a prototype of the mechanism was produced,and a seedling-feeding experiment was carried out.One-thousand seedlings were tested at a rate of 100 seedlings per minute,and the statistical success rate was 93.4%.Thus,the automatic scallion-seedling feeding mechanism significantly improves the e ciency of automatically transplanting scallions.
文摘[Objectives] This study was conducted to explore the dissipation dynamics of chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile) in scallion.[Methods] The level of residue and the dissipation of chlorothalonil and its main metabolite 4-hydroxy-2,5,6-trichloroisophthalonitrile in scallion in Beijing and Jiangsu experimental bases were determined via acetonitrile extraction and ultra-performance liquid chromatography coupled with ultraviolet detection (UPLC-UV).[Results] The dissipation of chlorothalonil in scallion followed the first-order kinetic model and the half-life of chlorothalonil in scallion was 3.5-4.1 d. The final residue of chlorothalonil in scallion decreased over time after the last application. After chlorothalonil was applied at 1 050 or 1 575 g a.i./hm 2 3 or 4 times, the maximum residue level of chlorothalonil was 1.48, 1.21, 0.72 and 0.45 mg/kg 5, 7, 10 and 14 d after the last application, while that of its 4-hydroxy metabolite was 0.25, 0.19, 0.13 and 0.09 mg/kg, respectively.[Conclusions] The results may provide experimental evidence for evaluating the safety of the use of chlorothalonil in scallion.
基金Supported by the Special Project for the Reform of Scientific Research Organization for No-profits(pzsfyl-201812)
文摘[Objectives] The aim was to reveal the distribution of soil organic matter content in cultivated land in the Se-rich areas of Hainan in 1980and 2010, so as to provide reference for the study on the evolution of soil organic matter content.[Methods] With the combination of field investigation with indoor analysis, the characteristics of organic matter content in the Se-rich areas of Hainan in 1980 and 2010 was revealed by means of spatial analysis, and the differences were analyzed.[Results] In the last 30 years, the proportion of 20-30 g/kg of soil organic matter content in the Se-rich areas of Hainan was reduced, but the content of soil organic matter in the area generally increased. The average value of the content of organic matter in the area was increased from 25.3 g/kg in the 1980s to 28.1 g/kg, but its spatial distribution was uneven.[Conclusions] The farmers should be guided to change the fertilization structure, and attention should be paid to the application of organic fertilizer, so as to improve the soil organic matter content.
基金Supported by Guangxi Science and Technology Plan Item(Guangxi Science AA17202037,Guangxi Science AB16380164,2015GXNSFAA139101)Xixiangtang Science and Technology Item of Nanning City(201710304)
文摘Se is one of trace elements necessary for the human body,and human body could absorb Se via the food. Se intake is insufficient in 2/3 region of China,which seriously affects health of local residents. Therefore,the research of Se-rich fertilizer and the development of Se-rich product become the research focus in food science,medicine and other fields. There are rich marine resources in Beibu Gulf waters of Guangxi,and much carapace organic waste is generated. These carapace waste not only has high Se content but also is composed of a lot of Ca. The preparation of Se-rich & high-Ca fertilizer by these carapace waste not only reaches the target of recycling and environment friendly but also increases the yield of agricultural products,reduces diseases and pests,improves quality,increases the added value of agricultural product,which brings better economic benefit and meets people's demand for healthy food.