风云三号C星（FY-3C）已经于2013年9月23日发射升空,其上装载的微波湿温探测仪（MWHTS）已于9月30日开机正常工作.MWHTS具有对大气温度和湿度垂直分布进行同步探测的能力.MWHTS为跨轨扫描式微波辐射计,在89-191GHz毫米波段内设置了十五...风云三号C星（FY-3C）已经于2013年9月23日发射升空,其上装载的微波湿温探测仪（MWHTS）已于9月30日开机正常工作.MWHTS具有对大气温度和湿度垂直分布进行同步探测的能力.MWHTS为跨轨扫描式微波辐射计,在89-191GHz毫米波段内设置了十五个探测通道,其中包括118.75GHz氧气吸收线附近的8个大气温度探测通道,183.31GHz水汽吸收线附近的5个大气湿度探测通道,以及89GHz和150GHz两个窗区通道.设置在118.75GHz的一组毫米波探测通道是国际上业务卫星首次使用的大气探测通道,这组通道和183.31GHz通道对大气进行联合探测,将获得更加精细的大气温湿度垂直分布数据,为数值预报和气候研究提供丰富信息.为保证MWHTS观测资料的定量应用,对仪器性能和定标精度进行了在轨测试.利用MWHTS在轨正常工作后的三个月数据,对仪器在轨定标的基础数据：冷空和黑体计数值,黑体和仪器温度进行监测分析和质量检验,经过质量检验的在轨定标基础数据,结合发射前真空试验得到的非线性订正项在轨定标生成MWHTS观测亮温数据.评估MWHTS在轨辐射定标结果的精度和偏差特性使用了三种方法：1通过场地定标试验获取大气温湿廓线和地面温度等大气参数信息,结合微波逐线正演辐射传输模式MonoRTM（Monochromatic Radiative Transfer Model）模拟MWHTS的上行微波辐射亮温,与MWHTS实际观测结果进行对比分析;2两个通道特性一致的同类星载被动微波载荷同时观测同一目标,观测亮温的差异主要取决于两个载荷的定标系统偏差.选取美国SNPP上搭载的微波探测仪器ATMS作为MWHTS的参考载荷,基于SNO（simultaneous nadir overpass）技术,对两个仪器的观测亮温进行交叉比对,观测亮温时空匹配及均匀性检验的条件为：观测时间差异小于20min,观测像元中心距离小于3km,观测角度在星下点附近差异小于5°,观测像元周围3×3像元内的亮展开更多
To simulate the bending behavior of wheat straw,a flexible straw model was developed based on the Hertz-Mindlin with bonding model using discrete element method.The proposed model was constructed by bonding straw unit...To simulate the bending behavior of wheat straw,a flexible straw model was developed based on the Hertz-Mindlin with bonding model using discrete element method.The proposed model was constructed by bonding straw units(filled by multi-spherical method)through parallel bonding keys.By means of a three-point bending test,single-factor sensitivity analysis and calibration of bonding parameters were performed.Results showed that elastic modulus of the flexible straw enhanced with the increase of bonded disk radius,normal stiffness per unit area and shear stiffness per unit area.The three bonding parameters were respectively calibrated to be 2.11 mm,9.48×10^(9)N/m^(3)and 4.67×10^(9)N/m^(3) by solving the regression equation developed from Box-Behnken design.The simulated elastic modulus(in terms of those three calibrated parameters)exhibited 4.20%difference with the measured one.It proved that the flexible straw could accurately demonstrate bending property of the wheat straw.This would not only help to improve accuracy in simulating wheat straw,but also provide references for flexible straw modeling and parameters calibration of other crops.展开更多
文摘风云三号C星（FY-3C）已经于2013年9月23日发射升空,其上装载的微波湿温探测仪（MWHTS）已于9月30日开机正常工作.MWHTS具有对大气温度和湿度垂直分布进行同步探测的能力.MWHTS为跨轨扫描式微波辐射计,在89-191GHz毫米波段内设置了十五个探测通道,其中包括118.75GHz氧气吸收线附近的8个大气温度探测通道,183.31GHz水汽吸收线附近的5个大气湿度探测通道,以及89GHz和150GHz两个窗区通道.设置在118.75GHz的一组毫米波探测通道是国际上业务卫星首次使用的大气探测通道,这组通道和183.31GHz通道对大气进行联合探测,将获得更加精细的大气温湿度垂直分布数据,为数值预报和气候研究提供丰富信息.为保证MWHTS观测资料的定量应用,对仪器性能和定标精度进行了在轨测试.利用MWHTS在轨正常工作后的三个月数据,对仪器在轨定标的基础数据：冷空和黑体计数值,黑体和仪器温度进行监测分析和质量检验,经过质量检验的在轨定标基础数据,结合发射前真空试验得到的非线性订正项在轨定标生成MWHTS观测亮温数据.评估MWHTS在轨辐射定标结果的精度和偏差特性使用了三种方法：1通过场地定标试验获取大气温湿廓线和地面温度等大气参数信息,结合微波逐线正演辐射传输模式MonoRTM（Monochromatic Radiative Transfer Model）模拟MWHTS的上行微波辐射亮温,与MWHTS实际观测结果进行对比分析;2两个通道特性一致的同类星载被动微波载荷同时观测同一目标,观测亮温的差异主要取决于两个载荷的定标系统偏差.选取美国SNPP上搭载的微波探测仪器ATMS作为MWHTS的参考载荷,基于SNO（simultaneous nadir overpass）技术,对两个仪器的观测亮温进行交叉比对,观测亮温时空匹配及均匀性检验的条件为：观测时间差异小于20min,观测像元中心距离小于3km,观测角度在星下点附近差异小于5°,观测像元周围3×3像元内的亮
基金This research was financially supported by Research Fund for the Doctoral Program of Higher Education of China(Grant No.20130204110020).
文摘To simulate the bending behavior of wheat straw,a flexible straw model was developed based on the Hertz-Mindlin with bonding model using discrete element method.The proposed model was constructed by bonding straw units(filled by multi-spherical method)through parallel bonding keys.By means of a three-point bending test,single-factor sensitivity analysis and calibration of bonding parameters were performed.Results showed that elastic modulus of the flexible straw enhanced with the increase of bonded disk radius,normal stiffness per unit area and shear stiffness per unit area.The three bonding parameters were respectively calibrated to be 2.11 mm,9.48×10^(9)N/m^(3)and 4.67×10^(9)N/m^(3) by solving the regression equation developed from Box-Behnken design.The simulated elastic modulus(in terms of those three calibrated parameters)exhibited 4.20%difference with the measured one.It proved that the flexible straw could accurately demonstrate bending property of the wheat straw.This would not only help to improve accuracy in simulating wheat straw,but also provide references for flexible straw modeling and parameters calibration of other crops.
