This paper has systematically investigated the substrate temperature and thickness dependence of surface morphology and magnetic property of CrAs compound films grown on GaAs by molecular-beam epitaxy. It finds that t...This paper has systematically investigated the substrate temperature and thickness dependence of surface morphology and magnetic property of CrAs compound films grown on GaAs by molecular-beam epitaxy. It finds that the substrate temperature affects the surface morphology and magnetic property of CrAs thin film more potently than the thickness.展开更多
High quality single crystal CrAs was grown by Sn flux method.The results of magnetic susceptibility and electrical resistivity are reported in a temperature range of 2 to 800 K.At low temperatures,a T2 dependence of r...High quality single crystal CrAs was grown by Sn flux method.The results of magnetic susceptibility and electrical resistivity are reported in a temperature range of 2 to 800 K.At low temperatures,a T2 dependence of resistivity is observed showing a Fermi-liquid behavior.The Kadowaki-Woods ratio is found to be 1×10-5 μΩ cm mol2 K2 mJ-2,which fits well to the universal value for many correlated electron systems.At about 270 K,a clear magnetic transition is observed with sharp changes of resistivity and susceptibility.Above 270 K,a linear-temperature dependence of the magnetic susceptibility is observed up to 700 K,which resembles the T-dependent magnetic susceptibility of parents of iron-pnictides superconductors.展开更多
大气延迟是合成孔径雷达干涉测量(interferometric synthetic aperture radar,InSAR)地表形变监测的主要误差源之一。提出采用中国第一代全球大气和陆面再分析产品(China’s first generation global atmospheric and land reanalysis p...大气延迟是合成孔径雷达干涉测量(interferometric synthetic aperture radar,InSAR)地表形变监测的主要误差源之一。提出采用中国第一代全球大气和陆面再分析产品(China’s first generation global atmospheric and land reanalysis product,CRA)数据改正InSAR对流层延迟,并采用小基线集InSAR(small baseline subset InSAR,SBAS-InSAR)技术对南加州的地表变形监测进行了详细分析与评估。首先提出了利用该产品计算对流层延迟的方法,通过顾及大气参数垂直分层及水平变化的物理特性,分别对该产品原始气象参数进行垂直向和水平向的插值,沿卫星视线方向积分计算大气延迟,通过与原始干涉图差分,得到大气改正结果;然后将结果从干涉图相位标准差、空间相关性和相位-高程相关系数3个方面进行误差分析;最后利用Sentinel-1数据进行南加州形变测量实验,将该方法与经典SBAS-InSAR结果进行对比,使用全球定位系统数据进行验证。结果表明:(1)校正后的干涉图平均标准差减小了34.7%,65%的干涉图平均标准差减小了20%以上;(2)干涉图空间结构函数的期望平方差显著性下降表明该产品能有效抑制长波大气;(3)相关性的拟合系数变化表明该产品能够有效降低高程影响带来的大气垂直分层分量;(4)说明利用分辨率较低的全球大气模型数据进行大气改正时考虑对流层空间变化的有效性。所得结果说明了CRA产品在InSAR大气校正上的可行性。展开更多
目前数字射线检测(DR)已广泛应用在陆地工程建设无损检测领域,目前在国内,海底管道环焊缝检测尚未有DR设备的大规模使用,DR在CRA海管根焊的提前检测中具有良好效果。但是DR在标准要求下是否满足图像质量与胶片射线检验的等价性是需要关...目前数字射线检测(DR)已广泛应用在陆地工程建设无损检测领域,目前在国内,海底管道环焊缝检测尚未有DR设备的大规模使用,DR在CRA海管根焊的提前检测中具有良好效果。但是DR在标准要求下是否满足图像质量与胶片射线检验的等价性是需要关注的问题。本文通过计算方法对DNV GL ST F101-2021、ISO 17636-2022标准的数字射线与胶片射线进行了技术等价性分析,认为DR能够满足海上海管检验环焊缝检验的等价性要求。展开更多
Precipitable Water Vapor(PWV)is a crucial parameter for short-term climate warnings and long-term climate monitoring.Due to their seamless spatiotemporal coverage,atmospheric reanalysis products provide excellent PWV ...Precipitable Water Vapor(PWV)is a crucial parameter for short-term climate warnings and long-term climate monitoring.Due to their seamless spatiotemporal coverage,atmospheric reanalysis products provide excellent PWV datasets for related research.At present,multiple research institutes continue to release long-term reanalysis PWV products,maintaining a steady output over time.However,comprehensive evaluation reports comparing these products are lacking.This paper therefore uses global radiosonde(RS)data from 2019 as a reference to first compare and evaluate the accuracy of four widelyused reanalysis datasets:the European Centre for Medium-RangeWeather Forecasts reanalysis version 5(ERA5),the Japanese 55-year Reanalysis(JRA55),the Second Modern-Era Retrospective Analysis for Research and Applications(MERRA2),and the global atmospheric reanalysis by the China Meteorological Administration(CRA40).The evaluation results show that the PWV values from all four reanalysis products are highly consistent with RS PWV.The RMSE and correlation coefficients for ERA5,CRA40,MERRA2,and JRA55 were 2.09 mm/0.99,2.31 mm/0.98,2.86 mm/0.97,and 2.80 mm/0.97,respectively.ERA5,JRA55,and CRA40 products exhibited a negative bias,while only the MERRA2 overestimated PWV.Overall,the product accuracy ranks from highest to lowest are ERA5,CRA40,MERRA2,and JRA55.All four products are affected by altitude and season,with lower accuracy observed at low altitudes and during high-precipitation seasons.Notably,CRA40,the first global reanalysis product from the China Meteorological Administration,has demonstrated comparable accuracy to the latest ERA5 in the Chinese mainland.Given its strong potential,CRA40 merits greater attention and wider adoption.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10334030, 10425419 and 60521001）. Acknowledgments The authors acknowledge Professor Z.C. Niu, Professor F.H. Yang and Professor H.Z. Zheng for useful discussion.
文摘This paper has systematically investigated the substrate temperature and thickness dependence of surface morphology and magnetic property of CrAs compound films grown on GaAs by molecular-beam epitaxy. It finds that the substrate temperature affects the surface morphology and magnetic property of CrAs thin film more potently than the thickness.
基金supported by the National Natural Science Foundation of China,the Knowledge Innovation Project of Chinese Academy of Sciencesthe 973 Project of the MOST of China
文摘High quality single crystal CrAs was grown by Sn flux method.The results of magnetic susceptibility and electrical resistivity are reported in a temperature range of 2 to 800 K.At low temperatures,a T2 dependence of resistivity is observed showing a Fermi-liquid behavior.The Kadowaki-Woods ratio is found to be 1×10-5 μΩ cm mol2 K2 mJ-2,which fits well to the universal value for many correlated electron systems.At about 270 K,a clear magnetic transition is observed with sharp changes of resistivity and susceptibility.Above 270 K,a linear-temperature dependence of the magnetic susceptibility is observed up to 700 K,which resembles the T-dependent magnetic susceptibility of parents of iron-pnictides superconductors.
文摘大气延迟是合成孔径雷达干涉测量(interferometric synthetic aperture radar,InSAR)地表形变监测的主要误差源之一。提出采用中国第一代全球大气和陆面再分析产品(China’s first generation global atmospheric and land reanalysis product,CRA)数据改正InSAR对流层延迟,并采用小基线集InSAR(small baseline subset InSAR,SBAS-InSAR)技术对南加州的地表变形监测进行了详细分析与评估。首先提出了利用该产品计算对流层延迟的方法,通过顾及大气参数垂直分层及水平变化的物理特性,分别对该产品原始气象参数进行垂直向和水平向的插值,沿卫星视线方向积分计算大气延迟,通过与原始干涉图差分,得到大气改正结果;然后将结果从干涉图相位标准差、空间相关性和相位-高程相关系数3个方面进行误差分析;最后利用Sentinel-1数据进行南加州形变测量实验,将该方法与经典SBAS-InSAR结果进行对比,使用全球定位系统数据进行验证。结果表明:(1)校正后的干涉图平均标准差减小了34.7%,65%的干涉图平均标准差减小了20%以上;(2)干涉图空间结构函数的期望平方差显著性下降表明该产品能有效抑制长波大气;(3)相关性的拟合系数变化表明该产品能够有效降低高程影响带来的大气垂直分层分量;(4)说明利用分辨率较低的全球大气模型数据进行大气改正时考虑对流层空间变化的有效性。所得结果说明了CRA产品在InSAR大气校正上的可行性。
文摘目前数字射线检测(DR)已广泛应用在陆地工程建设无损检测领域,目前在国内,海底管道环焊缝检测尚未有DR设备的大规模使用,DR在CRA海管根焊的提前检测中具有良好效果。但是DR在标准要求下是否满足图像质量与胶片射线检验的等价性是需要关注的问题。本文通过计算方法对DNV GL ST F101-2021、ISO 17636-2022标准的数字射线与胶片射线进行了技术等价性分析,认为DR能够满足海上海管检验环焊缝检验的等价性要求。
基金supported by the National Natural Science Foundation of China(42304022,42330105)Natural Science Foundation of Hubei Province of China(2023AFB058)Natural Science Foundation of Wuhan(2024040801020237).
文摘Precipitable Water Vapor(PWV)is a crucial parameter for short-term climate warnings and long-term climate monitoring.Due to their seamless spatiotemporal coverage,atmospheric reanalysis products provide excellent PWV datasets for related research.At present,multiple research institutes continue to release long-term reanalysis PWV products,maintaining a steady output over time.However,comprehensive evaluation reports comparing these products are lacking.This paper therefore uses global radiosonde(RS)data from 2019 as a reference to first compare and evaluate the accuracy of four widelyused reanalysis datasets:the European Centre for Medium-RangeWeather Forecasts reanalysis version 5(ERA5),the Japanese 55-year Reanalysis(JRA55),the Second Modern-Era Retrospective Analysis for Research and Applications(MERRA2),and the global atmospheric reanalysis by the China Meteorological Administration(CRA40).The evaluation results show that the PWV values from all four reanalysis products are highly consistent with RS PWV.The RMSE and correlation coefficients for ERA5,CRA40,MERRA2,and JRA55 were 2.09 mm/0.99,2.31 mm/0.98,2.86 mm/0.97,and 2.80 mm/0.97,respectively.ERA5,JRA55,and CRA40 products exhibited a negative bias,while only the MERRA2 overestimated PWV.Overall,the product accuracy ranks from highest to lowest are ERA5,CRA40,MERRA2,and JRA55.All four products are affected by altitude and season,with lower accuracy observed at low altitudes and during high-precipitation seasons.Notably,CRA40,the first global reanalysis product from the China Meteorological Administration,has demonstrated comparable accuracy to the latest ERA5 in the Chinese mainland.Given its strong potential,CRA40 merits greater attention and wider adoption.
