Al_(2)O_(3)–SiO_(2)sols were synthesized by using aluminum chloride hex hydrate and tetraethoxysilane(TEOS)as precursors,deionized water and ethanol mixture as the solvent,and propylene oxide as the coagulant aids.Al...Al_(2)O_(3)–SiO_(2)sols were synthesized by using aluminum chloride hex hydrate and tetraethoxysilane(TEOS)as precursors,deionized water and ethanol mixture as the solvent,and propylene oxide as the coagulant aids.Alumina coatings were prepared on the surfaces of hollow quartz filament fiber,then a new lightweight and thermal insulating material were successfully prepared by impregnatingAl_(2)O_(3)–SiO_(2)sol into a needle fabric made by coated hollow quartz filament fiber.The coated quartz fiber,aerogels and composites were characterized by Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),energy dispersive spectroscopy(EDS),nitrogen adsorption-desorption(BET),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and tensile tests.The effects of different fiber and calcination temperatures on the microstructures and properties ofAl_(2)O_(3)–SiO_(2)composite aerogels were investigated.The test results indicate that the mechanical properties of the aerogels are improved by introducing quartz filament fabrics and the introduction of alumina coating improves the thermal stability of the material.Compared to other fibers,Al_(2)O_(3)-coated hollow quartz fiber has significant advantages as reinforcement for composite,and their tensile strength is well retained after high temperature heat treatment.展开更多
利用FY-2G静止卫星数据反演的云宏微观特征参量(简称“云参量”),对2018—2020年青海全省及3个子研究区云参量时空分布特征进行分析。结果表明:云顶高度(cloud top height,CTH)、云顶温度(cloud top temperature,CTT)、过冷层厚度(overc...利用FY-2G静止卫星数据反演的云宏微观特征参量(简称“云参量”),对2018—2020年青海全省及3个子研究区云参量时空分布特征进行分析。结果表明:云顶高度(cloud top height,CTH)、云顶温度(cloud top temperature,CTT)、过冷层厚度(overcooled layer depth,OLD)、云光学厚度(cloud op⁃tical depth,COD)、云粒子有效半径(effective radius,ER)及液水路径(liquid water path,LWP)6个云参量全省区域年平均值分别为3.8 km、-9.7℃、2.0 km、7.1、7.1μm及63.7 g∙m^(-2)。纬度相同的柴达木盆地、青海东北部除CTT外,其余云参量月变化大致呈双峰双谷分布,峰值基本出现在5、11月,谷值基本出现在8、9月及12、1月,三江源各云参量大致呈单峰分布,峰值基本在11月。各云参量年平均值空间分布均呈沿地形和山脉走向分布的特征,除CTT外,其余云参量高值区与高大山脉相对应、低值区与沙漠盆地及低海拔地区相对应,柴达木盆地在四季均存在一低值区,夏季低值区范围最大,三江源地区及青海祁连山区在春、冬季存在明显高值区。三江源地区OLD、COD及LWP在春季及秋季较大,青海东北部地区OLD、LWP在春季最大,而春、秋季则是进行以水源涵养、抗旱减灾等为目的的人工增雨作业的较佳时机。展开更多
文摘Al_(2)O_(3)–SiO_(2)sols were synthesized by using aluminum chloride hex hydrate and tetraethoxysilane(TEOS)as precursors,deionized water and ethanol mixture as the solvent,and propylene oxide as the coagulant aids.Alumina coatings were prepared on the surfaces of hollow quartz filament fiber,then a new lightweight and thermal insulating material were successfully prepared by impregnatingAl_(2)O_(3)–SiO_(2)sol into a needle fabric made by coated hollow quartz filament fiber.The coated quartz fiber,aerogels and composites were characterized by Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),energy dispersive spectroscopy(EDS),nitrogen adsorption-desorption(BET),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and tensile tests.The effects of different fiber and calcination temperatures on the microstructures and properties ofAl_(2)O_(3)–SiO_(2)composite aerogels were investigated.The test results indicate that the mechanical properties of the aerogels are improved by introducing quartz filament fabrics and the introduction of alumina coating improves the thermal stability of the material.Compared to other fibers,Al_(2)O_(3)-coated hollow quartz fiber has significant advantages as reinforcement for composite,and their tensile strength is well retained after high temperature heat treatment.
文摘利用FY-2G静止卫星数据反演的云宏微观特征参量(简称“云参量”),对2018—2020年青海全省及3个子研究区云参量时空分布特征进行分析。结果表明:云顶高度(cloud top height,CTH)、云顶温度(cloud top temperature,CTT)、过冷层厚度(overcooled layer depth,OLD)、云光学厚度(cloud op⁃tical depth,COD)、云粒子有效半径(effective radius,ER)及液水路径(liquid water path,LWP)6个云参量全省区域年平均值分别为3.8 km、-9.7℃、2.0 km、7.1、7.1μm及63.7 g∙m^(-2)。纬度相同的柴达木盆地、青海东北部除CTT外,其余云参量月变化大致呈双峰双谷分布,峰值基本出现在5、11月,谷值基本出现在8、9月及12、1月,三江源各云参量大致呈单峰分布,峰值基本在11月。各云参量年平均值空间分布均呈沿地形和山脉走向分布的特征,除CTT外,其余云参量高值区与高大山脉相对应、低值区与沙漠盆地及低海拔地区相对应,柴达木盆地在四季均存在一低值区,夏季低值区范围最大,三江源地区及青海祁连山区在春、冬季存在明显高值区。三江源地区OLD、COD及LWP在春季及秋季较大,青海东北部地区OLD、LWP在春季最大,而春、秋季则是进行以水源涵养、抗旱减灾等为目的的人工增雨作业的较佳时机。
