The effect of nitrogen on the microstructure and secondary hardening of H21 die steel was studied by using scanning electron microscope, X-ray diffraction, transmission electron microscope and dilatometer. The results...The effect of nitrogen on the microstructure and secondary hardening of H21 die steel was studied by using scanning electron microscope, X-ray diffraction, transmission electron microscope and dilatometer. The results demonstrate that nitrogen can enhance the secondary hardening behavior of H21 hot-working die steel without toughness lose. Nitrogen addition increases the austenitic phase zone, decreasing austenite transformation temperature and martensite transformation temperature, thereby increasing the retained austenite stability. Retained austenite in quenched steel can dissolve a large quantity of alloy, thereby decreasing the coarsening rate of the precipitates. Trace nitrogen could intensify the refinement of pearlite by decreasing the diffusion rate of alloying element into carbides. Nitrogen increases the amounts and precipitation temperature of the undissolved V(C, N) and suppresses the growth of prior austenite before quenching. During tempering process, parts of nitrogen in V(C, N) dissolved back into the matrix, resulting in the distorting lattice of ferrite, thereby reinforcing the matrix. Meanwhile, the solid-dissolved nitrogen inhibits the growth of carbides by decreasing the diffusion rate of alloying elements.展开更多
目的建立蒙药玉簪花中山奈酚-7-O-β-D-葡萄糖苷的含量测定方法。方法采用HPLC法,色谱柱为Phenomenex Luna C18(250mm×4.6mm,5μm),以体积分数为0.5%的磷酸水溶液-甲醇为流动相,梯度洗脱,检测波长为364nm。结果山奈酚-7-O-β-D-葡...目的建立蒙药玉簪花中山奈酚-7-O-β-D-葡萄糖苷的含量测定方法。方法采用HPLC法,色谱柱为Phenomenex Luna C18(250mm×4.6mm,5μm),以体积分数为0.5%的磷酸水溶液-甲醇为流动相,梯度洗脱,检测波长为364nm。结果山奈酚-7-O-β-D-葡萄糖苷质量在0.113～2.260μg内呈良好线性关系,相关系数为1,平均回收率为101.1%(RSD=2.58%,n=6)。结论玉簪花中山奈酚-7-O-β-D-葡萄糖苷的含量为0.2mg/g(0.02%),该方法简便、准确、重现性好,可用于蒙药玉簪花中山奈酚-7-O-β-D-葡萄糖苷的含量测定。展开更多
A fuzzy robust path tracking strategy of an active pelagic trawl system with ship and winch regulation is proposed.First,nonlinear mathematic model of the pelagic trawl system was derived using Lagrange equation and f...A fuzzy robust path tracking strategy of an active pelagic trawl system with ship and winch regulation is proposed.First,nonlinear mathematic model of the pelagic trawl system was derived using Lagrange equation and further simplified as a low order model for the convenience of controller design.Then,an active path tracking strategy of pelagic trawl system was investigated to improve the catching efficiency of the target fish near the sea bottom.By means of the active tracking control,the pelagic trawl net can be positioned dynamically to follow a specified trajectory via the coordinated winch and ship regulation.In addition,considering the system nonlinearities,modeling uncertainties and the unknown exogenous disturbance of the trawl system model,a nonlinear robust H2 /H∞ controller based on Takagi-Sugeno(T-S) fuzzy model was presented,and the simulation comparison with linear robust H2 /H∞ controller and PID method was conducted for the validation of the nonlinear fuzzy robust controller.The nonlinear simulation results show that the average tracking error is 0.4 m for the fuzzy robust H2 /H∞ control and 125.8 m for the vertical and horizontal displacement,respectively,which is much smaller than linear H2 /H∞ controller and the PID controller.The investigation results illustrate that the fuzzy robust controller is effective for the active path tracking control of the pelagic trawl system.展开更多
Structures of 2-(naphthalen-2-ylmethyl)-2,3-dihydro-1H-indene-1,2-diol (C20H18O2), compound 1 and 1-(3,4-dimethoxyphenyl)-3-methoxy-3-(4-nitrophenyl)propane-1,2-diol chloroform (C18H21NO7·CHCl3) compound 2 were e...Structures of 2-(naphthalen-2-ylmethyl)-2,3-dihydro-1H-indene-1,2-diol (C20H18O2), compound 1 and 1-(3,4-dimethoxyphenyl)-3-methoxy-3-(4-nitrophenyl)propane-1,2-diol chloroform (C18H21NO7·CHCl3) compound 2 were established by spectral and X-ray diffraction studies. Compound 1 crystallizes in the orthorhombic space group P212121 with unit cell parameters a = 5.2177 (6), b = 13.903 (2), c = 21.121 (2) A, Z = 4. Compound 2 crystallizes in the triclinic space group P-1 with unit cell parameters a = 9.238 (1), b = 9.879 (1), c = 12.636 (1) A, α = 102.004 (1), β = 92.356 (1), γ = 90.779 (1)o, Z = 2. These two new molecules arise from a facile preparation of 1,2-diols from chalcones and have been fully characterized. Based on the crystallographic information obtained for compound 1, the relative configuration for the chiral centers is 1S and 2S. In structure 1, both hydroxyl groups adopt an anti-conformation with a torsion angle O1-C1-C2-O2 value of 93.1 (2)o [in molecule 2, both hydroxyl groups adopt a trans-conformation with a torsion angle O1-C1-C2-O2 value of -171.0 (2)。]. In both structures, the molecules in the crystal are linked by intermolecular hydrogen bonds O-H···O and C-H···O interactions and adjacent molecules are interconnected by intermolecular weak C-H···π and C-H···Cl interactions which give additional support to molecular packing stability.展开更多
基金National Key Research and Development Program of China (2016YFB0300200)National Natural Science Foundation of China (Grant No. U1660114).
文摘The effect of nitrogen on the microstructure and secondary hardening of H21 die steel was studied by using scanning electron microscope, X-ray diffraction, transmission electron microscope and dilatometer. The results demonstrate that nitrogen can enhance the secondary hardening behavior of H21 hot-working die steel without toughness lose. Nitrogen addition increases the austenitic phase zone, decreasing austenite transformation temperature and martensite transformation temperature, thereby increasing the retained austenite stability. Retained austenite in quenched steel can dissolve a large quantity of alloy, thereby decreasing the coarsening rate of the precipitates. Trace nitrogen could intensify the refinement of pearlite by decreasing the diffusion rate of alloying element into carbides. Nitrogen increases the amounts and precipitation temperature of the undissolved V(C, N) and suppresses the growth of prior austenite before quenching. During tempering process, parts of nitrogen in V(C, N) dissolved back into the matrix, resulting in the distorting lattice of ferrite, thereby reinforcing the matrix. Meanwhile, the solid-dissolved nitrogen inhibits the growth of carbides by decreasing the diffusion rate of alloying elements.
文摘目的建立蒙药玉簪花中山奈酚-7-O-β-D-葡萄糖苷的含量测定方法。方法采用HPLC法,色谱柱为Phenomenex Luna C18(250mm×4.6mm,5μm),以体积分数为0.5%的磷酸水溶液-甲醇为流动相,梯度洗脱,检测波长为364nm。结果山奈酚-7-O-β-D-葡萄糖苷质量在0.113～2.260μg内呈良好线性关系,相关系数为1,平均回收率为101.1%(RSD=2.58%,n=6)。结论玉簪花中山奈酚-7-O-β-D-葡萄糖苷的含量为0.2mg/g(0.02%),该方法简便、准确、重现性好,可用于蒙药玉簪花中山奈酚-7-O-β-D-葡萄糖苷的含量测定。
基金Project(2009AA045004)supported by the Hi-tech Research and Development Program of China
文摘A fuzzy robust path tracking strategy of an active pelagic trawl system with ship and winch regulation is proposed.First,nonlinear mathematic model of the pelagic trawl system was derived using Lagrange equation and further simplified as a low order model for the convenience of controller design.Then,an active path tracking strategy of pelagic trawl system was investigated to improve the catching efficiency of the target fish near the sea bottom.By means of the active tracking control,the pelagic trawl net can be positioned dynamically to follow a specified trajectory via the coordinated winch and ship regulation.In addition,considering the system nonlinearities,modeling uncertainties and the unknown exogenous disturbance of the trawl system model,a nonlinear robust H2 /H∞ controller based on Takagi-Sugeno(T-S) fuzzy model was presented,and the simulation comparison with linear robust H2 /H∞ controller and PID method was conducted for the validation of the nonlinear fuzzy robust controller.The nonlinear simulation results show that the average tracking error is 0.4 m for the fuzzy robust H2 /H∞ control and 125.8 m for the vertical and horizontal displacement,respectively,which is much smaller than linear H2 /H∞ controller and the PID controller.The investigation results illustrate that the fuzzy robust controller is effective for the active path tracking control of the pelagic trawl system.
文摘Structures of 2-(naphthalen-2-ylmethyl)-2,3-dihydro-1H-indene-1,2-diol (C20H18O2), compound 1 and 1-(3,4-dimethoxyphenyl)-3-methoxy-3-(4-nitrophenyl)propane-1,2-diol chloroform (C18H21NO7·CHCl3) compound 2 were established by spectral and X-ray diffraction studies. Compound 1 crystallizes in the orthorhombic space group P212121 with unit cell parameters a = 5.2177 (6), b = 13.903 (2), c = 21.121 (2) A, Z = 4. Compound 2 crystallizes in the triclinic space group P-1 with unit cell parameters a = 9.238 (1), b = 9.879 (1), c = 12.636 (1) A, α = 102.004 (1), β = 92.356 (1), γ = 90.779 (1)o, Z = 2. These two new molecules arise from a facile preparation of 1,2-diols from chalcones and have been fully characterized. Based on the crystallographic information obtained for compound 1, the relative configuration for the chiral centers is 1S and 2S. In structure 1, both hydroxyl groups adopt an anti-conformation with a torsion angle O1-C1-C2-O2 value of 93.1 (2)o [in molecule 2, both hydroxyl groups adopt a trans-conformation with a torsion angle O1-C1-C2-O2 value of -171.0 (2)。]. In both structures, the molecules in the crystal are linked by intermolecular hydrogen bonds O-H···O and C-H···O interactions and adjacent molecules are interconnected by intermolecular weak C-H···π and C-H···Cl interactions which give additional support to molecular packing stability.
