基于CRU(Climate Research Unit)数据集1945—2019年咸海流域月降水序列,利用气候倾向率、集中度与分摊熵、样本熵与排列熵方法,分别分析了咸海流域年降水量变化、降水的年内分配、降水序列复杂性变化的时空特征,并用Mann-Kendall法检...基于CRU(Climate Research Unit)数据集1945—2019年咸海流域月降水序列,利用气候倾向率、集中度与分摊熵、样本熵与排列熵方法,分别分析了咸海流域年降水量变化、降水的年内分配、降水序列复杂性变化的时空特征,并用Mann-Kendall法检验了各方法所得结果的趋势性。结果表明:咸海流域年降水量总体基本保持不变,呈微弱的上升趋势,其中,流域西北部及中东部区域降水量呈显著上升的趋势;咸海流域降水集中于每年的3月左右,降水的年内分配有微弱的均匀化趋势,流域西部、北部及东部降水年内分配相对更均匀,流域中部及南部降水年内分配相对更集中;咸海流域西部、北部及东部降水序列的复杂性相对较高,中部及南部降水序列的复杂性相对较低,流域整体的降水序列的复杂性呈一定的上升趋势,其中,流域北部与南部降水序列的复杂性呈显著下降的趋势,流域西部、中部与东部降水序列的复杂性呈显著上升的趋势。展开更多
Pure Al and Al-30%Al_(2)O_(3)composite coatings are prepared on the surface of AZ31B magnesium alloy by low-pressure cold spraying.The morphology and structure of the coatings are analyzed by scanning electron microsc...Pure Al and Al-30%Al_(2)O_(3)composite coatings are prepared on the surface of AZ31B magnesium alloy by low-pressure cold spraying.The morphology and structure of the coatings are analyzed by scanning electron microscope (SEM),energy dispersive spectroscopy (EDS),and X-ray diffraction (XRD),and the effects of the addition of Al_(2)O_(3)on the microstructure of the Al-based coatings are discussed.The mechanical properties and corrosion resistance of the coatings are fully evaluated by the micro-hardness tester,electronic tensile machine,and electrochemical workstation.The results show that the coating structure is more uniform and denser,and the porosity is significantly reduced after the addition of Al_(2)O_(3).The interfaces between the coatings and the magnesium alloy substrate are distinct,and the coatings and the substrate are mechanically combined.Compared with the pure Al coating,the microhardness of the Al-Al_(2)O_(3)composite coating is increased to 61.1 HV_(0.2),and the bonding strength reaches above 53.1 MPa.The self-corrosion potential of the two coatings is higher than that of the magnesium alloy,and the self-corrosion current density is significantly lower than that of the magnesium alloy substrate.The Al-based coatings prepared by low-pressure cold spraying have high hardness,good bonding strength,and good corrosion resistance,which can be used for the repair and protection of magnesium alloy structural parts.展开更多
文摘基于CRU(Climate Research Unit)数据集1945—2019年咸海流域月降水序列,利用气候倾向率、集中度与分摊熵、样本熵与排列熵方法,分别分析了咸海流域年降水量变化、降水的年内分配、降水序列复杂性变化的时空特征,并用Mann-Kendall法检验了各方法所得结果的趋势性。结果表明:咸海流域年降水量总体基本保持不变,呈微弱的上升趋势,其中,流域西北部及中东部区域降水量呈显著上升的趋势;咸海流域降水集中于每年的3月左右,降水的年内分配有微弱的均匀化趋势,流域西部、北部及东部降水年内分配相对更均匀,流域中部及南部降水年内分配相对更集中;咸海流域西部、北部及东部降水序列的复杂性相对较高,中部及南部降水序列的复杂性相对较低,流域整体的降水序列的复杂性呈一定的上升趋势,其中,流域北部与南部降水序列的复杂性呈显著下降的趋势,流域西部、中部与东部降水序列的复杂性呈显著上升的趋势。
文摘Pure Al and Al-30%Al_(2)O_(3)composite coatings are prepared on the surface of AZ31B magnesium alloy by low-pressure cold spraying.The morphology and structure of the coatings are analyzed by scanning electron microscope (SEM),energy dispersive spectroscopy (EDS),and X-ray diffraction (XRD),and the effects of the addition of Al_(2)O_(3)on the microstructure of the Al-based coatings are discussed.The mechanical properties and corrosion resistance of the coatings are fully evaluated by the micro-hardness tester,electronic tensile machine,and electrochemical workstation.The results show that the coating structure is more uniform and denser,and the porosity is significantly reduced after the addition of Al_(2)O_(3).The interfaces between the coatings and the magnesium alloy substrate are distinct,and the coatings and the substrate are mechanically combined.Compared with the pure Al coating,the microhardness of the Al-Al_(2)O_(3)composite coating is increased to 61.1 HV_(0.2),and the bonding strength reaches above 53.1 MPa.The self-corrosion potential of the two coatings is higher than that of the magnesium alloy,and the self-corrosion current density is significantly lower than that of the magnesium alloy substrate.The Al-based coatings prepared by low-pressure cold spraying have high hardness,good bonding strength,and good corrosion resistance,which can be used for the repair and protection of magnesium alloy structural parts.
