Radio Frequency Interference （RFI） causes severe contamination to passive and active microwave sensing observations and corresponding retrieval products. RFI signals should be detected and filtered before applying t...Radio Frequency Interference （RFI） causes severe contamination to passive and active microwave sensing observations and corresponding retrieval products. RFI signals should be detected and filtered before applying the microwave data to retrieval and data assimilation. It is difficult to detect RFI over land surfaces covered by snow because of the scattering effect of snow surface. The double principal component analysis （DPCA） method is adopted in this study, and its ability in identifying RFI signals in AMSR-E data over snow covered regions is investigated. Results show that the DPCA method can detect RFI signals effectively in spite of the impact of snow scattering, and the detected RFI signals persistent over time. Compared to other methods, such as PCA and normalized PCA, DPCA is more robust and suitable for operational application.展开更多
Solid base catalysts for the direct synthesis of dimethyl carbonate(DMC)from carbon dioxide,methanol,and propylene oxide were prepared by loading KCl and K_(2)CO_(3) on the surface of La_(2)O_(3),Y_(2)O_(3),CeO2 and N...Solid base catalysts for the direct synthesis of dimethyl carbonate(DMC)from carbon dioxide,methanol,and propylene oxide were prepared by loading KCl and K_(2)CO_(3) on the surface of La_(2)O_(3),Y_(2)O_(3),CeO2 and Nd_(2)O_(3).The catalysts were characterized by thermogravimetric analysis(TGA)and X-ray diffraction(XRD)techniques.The catalytic activities were efficiently influenced by the preparation conditions.The optimal loading amount of K_(2)CO_(3) is 17.6%(mass)for KCl-K_(2)CO_(3)/Y_(2)O_(3) and 22.2%for other catalysts.Supports affected the activity of catalyst.KCl-K_(2)CO_(3)/Nd_(2)O_(3) exhibited the highest activity.The activity of KCl-K_(2)CO_(3)/Y_(2)O_(3) increased with the increase of calcination temperature in the range of 800℃–900℃.The formation of KYO2,Y_(3)O_(4)Cl or YOX species probably promoted the catalysts.展开更多
文摘Radio Frequency Interference （RFI） causes severe contamination to passive and active microwave sensing observations and corresponding retrieval products. RFI signals should be detected and filtered before applying the microwave data to retrieval and data assimilation. It is difficult to detect RFI over land surfaces covered by snow because of the scattering effect of snow surface. The double principal component analysis （DPCA） method is adopted in this study, and its ability in identifying RFI signals in AMSR-E data over snow covered regions is investigated. Results show that the DPCA method can detect RFI signals effectively in spite of the impact of snow scattering, and the detected RFI signals persistent over time. Compared to other methods, such as PCA and normalized PCA, DPCA is more robust and suitable for operational application.
文摘Solid base catalysts for the direct synthesis of dimethyl carbonate(DMC)from carbon dioxide,methanol,and propylene oxide were prepared by loading KCl and K_(2)CO_(3) on the surface of La_(2)O_(3),Y_(2)O_(3),CeO2 and Nd_(2)O_(3).The catalysts were characterized by thermogravimetric analysis(TGA)and X-ray diffraction(XRD)techniques.The catalytic activities were efficiently influenced by the preparation conditions.The optimal loading amount of K_(2)CO_(3) is 17.6%(mass)for KCl-K_(2)CO_(3)/Y_(2)O_(3) and 22.2%for other catalysts.Supports affected the activity of catalyst.KCl-K_(2)CO_(3)/Nd_(2)O_(3) exhibited the highest activity.The activity of KCl-K_(2)CO_(3)/Y_(2)O_(3) increased with the increase of calcination temperature in the range of 800℃–900℃.The formation of KYO2,Y_(3)O_(4)Cl or YOX species probably promoted the catalysts.
