利用从MODIS Web Fire系统获取的2001—2009年陕西省内的热点数据,采用MODIS卫星的全球火点监测算法V04,分析得到陕西省地表热异常点发生分布的时空规律:2001—2005年逐年增加,2005—2009年逐年减少;每年的2—4月和6—7月为地表热异常...利用从MODIS Web Fire系统获取的2001—2009年陕西省内的热点数据,采用MODIS卫星的全球火点监测算法V04,分析得到陕西省地表热异常点发生分布的时空规律:2001—2005年逐年增加,2005—2009年逐年减少;每年的2—4月和6—7月为地表热异常点多发时段。林区热异常点的高峰期分别为3月(多发区为陕北的黄龙山林区和陕南的商洛市)及夏收后。展开更多
The structural, electronic, and optical properties of Zn3（VO4）2 are investigated using full potential linearized aug- mented plane wave （FP-LAPW） method within the framework of density functional theory （DFT）. V...The structural, electronic, and optical properties of Zn3（VO4）2 are investigated using full potential linearized aug- mented plane wave （FP-LAPW） method within the framework of density functional theory （DFT）. Various approaches are adopted to treat the exchange and correlation potential energy such as generalized gradient approximation （GGA）, GGA＋U, and the Tran-Blaha modified Becke-Johnson （TB-mBJ） potential. The calculated band gap of 3.424 eV by TB- mBJ is found to be close to the experimental result （3.3 eV）. The optical anisotropy is analyzed through optical constants, such as dielectric function and absorption coefficient along parallel and perpendicular crystal orientations. The absorption coefficient reveals high absorption （1.5 ×10^6cm^-1） of photons in the ultraviolet region.展开更多
The effect of Al-substitution on the electrochemical performances of Li3V2(PO4)3 cathode materials was studied.Samples with stoichiometric proportion of Li3AlxV2-x(PO4)3(x=0,0.05,0.10)were prepared by adding Al(NO3)3 ...The effect of Al-substitution on the electrochemical performances of Li3V2(PO4)3 cathode materials was studied.Samples with stoichiometric proportion of Li3AlxV2-x(PO4)3(x=0,0.05,0.10)were prepared by adding Al(NO3)3 in the raw materials of Li3V2(PO4)3.The XRD analysis shows that the Al-substituted Li3V2(PO4)3 has the same monoclinic structure as the un-substituted Li3V2(PO4)3.The SEM images show that Al-substituted Li3V2(PO4)3 has regular and uniform particles.The electrochemical measurements show that Al-substitution can improve the rate capability of cathode materials.The Li3Al0.05V1.95(PO4)3 sample shows the best high-rate performance.The discharge capacity at 1C rate is 119 mA·h/g with 30th capacity retention rate about 92.97%.The electrode reaction reversibility and electronic conductivity are enhanced,and the charge transfer resistance decreases through Al-substitution.The improved electrochemical performances of Al-substituted Li3V2(PO4)3 cathode materials offer some favorable properties for their commercial application.展开更多
文摘利用从MODIS Web Fire系统获取的2001—2009年陕西省内的热点数据,采用MODIS卫星的全球火点监测算法V04,分析得到陕西省地表热异常点发生分布的时空规律:2001—2005年逐年增加,2005—2009年逐年减少;每年的2—4月和6—7月为地表热异常点多发时段。林区热异常点的高峰期分别为3月(多发区为陕北的黄龙山林区和陕南的商洛市)及夏收后。
文摘The structural, electronic, and optical properties of Zn3（VO4）2 are investigated using full potential linearized aug- mented plane wave （FP-LAPW） method within the framework of density functional theory （DFT）. Various approaches are adopted to treat the exchange and correlation potential energy such as generalized gradient approximation （GGA）, GGA＋U, and the Tran-Blaha modified Becke-Johnson （TB-mBJ） potential. The calculated band gap of 3.424 eV by TB- mBJ is found to be close to the experimental result （3.3 eV）. The optical anisotropy is analyzed through optical constants, such as dielectric function and absorption coefficient along parallel and perpendicular crystal orientations. The absorption coefficient reveals high absorption （1.5 ×10^6cm^-1） of photons in the ultraviolet region.
基金Project(GuiJiaoRen[2007]71)supported by the Research Funds of the Guangxi Key Laboratory of Environmental Engineering,Protection and Assessment Program to Sponsor Teams for Innovation in the Construction of Talent Highlands in Guangxi Institutions of Higher Learning,China
文摘The effect of Al-substitution on the electrochemical performances of Li3V2(PO4)3 cathode materials was studied.Samples with stoichiometric proportion of Li3AlxV2-x(PO4)3(x=0,0.05,0.10)were prepared by adding Al(NO3)3 in the raw materials of Li3V2(PO4)3.The XRD analysis shows that the Al-substituted Li3V2(PO4)3 has the same monoclinic structure as the un-substituted Li3V2(PO4)3.The SEM images show that Al-substituted Li3V2(PO4)3 has regular and uniform particles.The electrochemical measurements show that Al-substitution can improve the rate capability of cathode materials.The Li3Al0.05V1.95(PO4)3 sample shows the best high-rate performance.The discharge capacity at 1C rate is 119 mA·h/g with 30th capacity retention rate about 92.97%.The electrode reaction reversibility and electronic conductivity are enhanced,and the charge transfer resistance decreases through Al-substitution.The improved electrochemical performances of Al-substituted Li3V2(PO4)3 cathode materials offer some favorable properties for their commercial application.
