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
为评价氰霜唑在葱上使用的安全性,开展了氰霜唑在葱上的残留情况及对人体的膳食摄入风险研究,进行了1年6地田间试验。消解动态试验按氰霜唑180 g a.i./ha(最高制剂量1.5倍)施药;最终残留试验氰霜唑低剂量按120 g a.i./ha,高剂量按180 g ...为评价氰霜唑在葱上使用的安全性,开展了氰霜唑在葱上的残留情况及对人体的膳食摄入风险研究,进行了1年6地田间试验。消解动态试验按氰霜唑180 g a.i./ha(最高制剂量1.5倍)施药;最终残留试验氰霜唑低剂量按120 g a.i./ha,高剂量按180 g a.i./ha施药,施药3~4次,施药间隔7 d,施药后7、10、14 d采集葱样品。氰霜唑及其代谢物CCIM利用超高效液相色谱-质谱联用仪(UPLC-MS/MS)定量分析检测。检测结果表明:氰霜唑在葱中的半衰期为3.9 d,降解较快。膳食风险评估结果表明:氰霜唑在登记作物中的总膳食评估值为0.12,膳食风险在可接受范围内,说明氰霜唑在葱中的残留不会对我国人体健康产生影响。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.
文摘为评价氰霜唑在葱上使用的安全性,开展了氰霜唑在葱上的残留情况及对人体的膳食摄入风险研究,进行了1年6地田间试验。消解动态试验按氰霜唑180 g a.i./ha(最高制剂量1.5倍)施药;最终残留试验氰霜唑低剂量按120 g a.i./ha,高剂量按180 g a.i./ha施药,施药3~4次,施药间隔7 d,施药后7、10、14 d采集葱样品。氰霜唑及其代谢物CCIM利用超高效液相色谱-质谱联用仪(UPLC-MS/MS)定量分析检测。检测结果表明:氰霜唑在葱中的半衰期为3.9 d,降解较快。膳食风险评估结果表明:氰霜唑在登记作物中的总膳食评估值为0.12,膳食风险在可接受范围内,说明氰霜唑在葱中的残留不会对我国人体健康产生影响。
