基于海洋二号D卫星(HY2D)2021年7月7-16日(年积日Day Of Year(DOY)188-197)的星载北斗观测数据,从测量数据有效性、可见卫星数量、位置精度因子及伪距多路径效应等角度分析了数据质量,并利用其进行事后精密定轨,从相位残差、重叠弧段、...基于海洋二号D卫星(HY2D)2021年7月7-16日(年积日Day Of Year(DOY)188-197)的星载北斗观测数据,从测量数据有效性、可见卫星数量、位置精度因子及伪距多路径效应等角度分析了数据质量,并利用其进行事后精密定轨,从相位残差、重叠弧段、轨道互比和激光检核4种手段评估了定轨结果精度.结论如下:(1)HY2D卫星接收北斗三号卫星数在4颗及以上占比约为86.66%;B1C频点多路径误差RMS(Root mean square)约为0.37 m,B2a频点约为0.18 m.(2)载波相位拟合残差RMS在6-8 mm之间;相邻轨道重叠4 h的位置差异小于2 cm,与法国CNES(Centre National d‘Etudes Spatiales)DORIS(Doppler Orbitography and Radio-positioning Integrated by Satellite)轨道比较径向RMS优于1.9 cm.(3)用激光测距数据检核轨道精度,其星距残差的RMS约为3.24 cm.结果表明,国产星载双频北斗接收机可以完成海洋测高卫星的精密定轨指标.展开更多
海洋一号C(HY-1C)卫星是中国首颗海洋水色业务卫星,其搭载的海岸带成像仪(Coastal Zone Imager, CZI)具有大幅宽、短重访周期的优势,可实现海洋和海岸带的大面积观测。作为光学传感器,CZI受云影响严重,准确识别云是CZI数据处理的关键,但...海洋一号C(HY-1C)卫星是中国首颗海洋水色业务卫星,其搭载的海岸带成像仪(Coastal Zone Imager, CZI)具有大幅宽、短重访周期的优势,可实现海洋和海岸带的大面积观测。作为光学传感器,CZI受云影响严重,准确识别云是CZI数据处理的关键,但是CZI缺少红外和短波红外等对云敏感的波段,云检测难度大。针对该问题,本文提出一种融合多尺度卷积和侧窗滤波的轻量化云检测方法,该方法通过多尺度卷积获取云的不同尺度特征,通过侧窗滤波突出边缘特征,减少椒盐噪声的影响,提升云边缘检测的精度。实验结果表明,本文所提出的方法可有效进行云检测,在云边缘提取方面表现较好,F1-score达92.77%,Kappa系数达0.89,与现有云检测方法相比优势明显,且模型训练速度快、参数量少,可为HY-1C CZI遥感影像处理提供有力支撑。展开更多
Purple-leafed plants not only have a higher resistance to biotic and abiotic stresses,but also have higher ornamental value.Anthocyanins are vital for leaf color formation,growth and development of purple leaves.Howev...Purple-leafed plants not only have a higher resistance to biotic and abiotic stresses,but also have higher ornamental value.Anthocyanins are vital for leaf color formation,growth and development of purple leaves.However,the molecular mechanism underlying purple leaf formation in Lagerstroemia indica remains unclear.Metabolomic and transcriptomic analysis of purple-leafed cultivar‘Ebony Embers’and greenleafed cultivar‘Arapahoe’showed that the high expression of anthocyanin structure genes induced hyperaccumulation of cyanidin and pelargonidin derivatives,making the leaves purple.LfiHY5,LfiMYB75 and LfibHLH1 were identified using correlation analysis and weighted gene co-expression network analysis.In‘Arapahoe’‘Ebony Embers’population,LfiHY5 and LfiMYB75 showed significant positive correlation with leaf anthocyanin content.Transient expression of LfiMYB75 and LfiHY5 in tobacco and purple-leafed crape myrtle indicated that the two genes activated anthocyanin synthesis.Yeast two-hybrid analysis showed that LfiMYB75 and LfibHLH1 could form a complex that enhanced anthocyanin synthesis.Yeast monohybrid and dual-luciferase assays confirmed that LfiHY5 activated the expression of LfiMYB75,to activate the transcription of anthocyanin structural genes LfiCHS and LfiANS.Moreover,there were three alleles of LfiHY5 in crape myrtle,and the different sequences had different activation effects on LfiMYB75.In conclusion,the results showed that LfiHY5 led to upregulate the transcription of LfiMYB75,and LfiMYB75 formed a complex with LfibHLH1,which increased the transcription level of LfiCHS and LfiANS to affect anthocyanin synthesis in crape myrtle.展开更多
Idiopathic acute pancreatitis is a diagnostic challenge for gastroenterologists.The possibility of finding a cause for pancreatitis usually relies on how far the diagnostic study is taken.Endoscopic explorations such ...Idiopathic acute pancreatitis is a diagnostic challenge for gastroenterologists.The possibility of finding a cause for pancreatitis usually relies on how far the diagnostic study is taken.Endoscopic explorations such as endoscopic retrograde cholangiopancreatography and endoscopic ultrasonography can help to determine the cause of pancreatitis.Furthermore,microscopic bile examination and magnetic resonance cholangiopancreatography can also be helpful in the work up of these patients.In this article an approximation to the diagnostic approach to patients with idiopathic acute pancreatitis is made,taking into account the reported evidence with which to choose between the different available explorations.展开更多
In this paper, the effect of adding different concentrations of kinetic inhibitors on the induction time of hydrogen sulfide hydrate formation in a reactor equipped with automatic adjustable temperature controller is ...In this paper, the effect of adding different concentrations of kinetic inhibitors on the induction time of hydrogen sulfide hydrate formation in a reactor equipped with automatic adjustable temperature controller is studied. A novel method namely ＂sudden cooling＂ is used for performing the relevant measurements, in which the induction time of H2S hydrate in the presence/absence of PVP and L-tyrosine with different concentrations （100, 500, and 1000 ppm） is determined. As a result, PVP with the concentration of 1000 ppm in aqueous solution is detected as a more suitable material for increasing the induction time of H2S hydrate formation among the investigated kinetic hydrate inhibitors.展开更多
A novel strategy, which is better-suited for preparing materials with a very microscopic structure, is described and the whisker-like composite of Co(OH) 2/HY was prepared by using this strategy. In addition, the mech...A novel strategy, which is better-suited for preparing materials with a very microscopic structure, is described and the whisker-like composite of Co(OH) 2/HY was prepared by using this strategy. In addition, the mechanism by which the growth proceeds is not very rigorously worked out. Due to the high dispersed capability of HY towards to Co(OH) 2 resulting in loose whisker-like microstructure of Co(OH) 2, small channels become available for the diffusion of OH - electrolyte ions through all Co(OH) 2 thin layer. Consequentially, the prepared composite shows a very high specific capacitance (483 F/g) and utilization (93%) of effective electroactive composition of composite.展开更多
文摘基于海洋二号D卫星(HY2D)2021年7月7-16日(年积日Day Of Year(DOY)188-197)的星载北斗观测数据,从测量数据有效性、可见卫星数量、位置精度因子及伪距多路径效应等角度分析了数据质量,并利用其进行事后精密定轨,从相位残差、重叠弧段、轨道互比和激光检核4种手段评估了定轨结果精度.结论如下:(1)HY2D卫星接收北斗三号卫星数在4颗及以上占比约为86.66%;B1C频点多路径误差RMS(Root mean square)约为0.37 m,B2a频点约为0.18 m.(2)载波相位拟合残差RMS在6-8 mm之间;相邻轨道重叠4 h的位置差异小于2 cm,与法国CNES(Centre National d‘Etudes Spatiales)DORIS(Doppler Orbitography and Radio-positioning Integrated by Satellite)轨道比较径向RMS优于1.9 cm.(3)用激光测距数据检核轨道精度,其星距残差的RMS约为3.24 cm.结果表明,国产星载双频北斗接收机可以完成海洋测高卫星的精密定轨指标.
文摘海洋一号C(HY-1C)卫星是中国首颗海洋水色业务卫星,其搭载的海岸带成像仪(Coastal Zone Imager, CZI)具有大幅宽、短重访周期的优势,可实现海洋和海岸带的大面积观测。作为光学传感器,CZI受云影响严重,准确识别云是CZI数据处理的关键,但是CZI缺少红外和短波红外等对云敏感的波段,云检测难度大。针对该问题,本文提出一种融合多尺度卷积和侧窗滤波的轻量化云检测方法,该方法通过多尺度卷积获取云的不同尺度特征,通过侧窗滤波突出边缘特征,减少椒盐噪声的影响,提升云边缘检测的精度。实验结果表明,本文所提出的方法可有效进行云检测,在云边缘提取方面表现较好,F1-score达92.77%,Kappa系数达0.89,与现有云检测方法相比优势明显,且模型训练速度快、参数量少,可为HY-1C CZI遥感影像处理提供有力支撑。
基金the National Key R and D Program of China(Grant Nos.2019YFD1000402,2019YFD1001004)the World-Class Discipline Construction and Characteristic Development Guidance Funds for Beijing Forestry University(Grant No.2019XKJS0323).
文摘Purple-leafed plants not only have a higher resistance to biotic and abiotic stresses,but also have higher ornamental value.Anthocyanins are vital for leaf color formation,growth and development of purple leaves.However,the molecular mechanism underlying purple leaf formation in Lagerstroemia indica remains unclear.Metabolomic and transcriptomic analysis of purple-leafed cultivar‘Ebony Embers’and greenleafed cultivar‘Arapahoe’showed that the high expression of anthocyanin structure genes induced hyperaccumulation of cyanidin and pelargonidin derivatives,making the leaves purple.LfiHY5,LfiMYB75 and LfibHLH1 were identified using correlation analysis and weighted gene co-expression network analysis.In‘Arapahoe’‘Ebony Embers’population,LfiHY5 and LfiMYB75 showed significant positive correlation with leaf anthocyanin content.Transient expression of LfiMYB75 and LfiHY5 in tobacco and purple-leafed crape myrtle indicated that the two genes activated anthocyanin synthesis.Yeast two-hybrid analysis showed that LfiMYB75 and LfibHLH1 could form a complex that enhanced anthocyanin synthesis.Yeast monohybrid and dual-luciferase assays confirmed that LfiHY5 activated the expression of LfiMYB75,to activate the transcription of anthocyanin structural genes LfiCHS and LfiANS.Moreover,there were three alleles of LfiHY5 in crape myrtle,and the different sequences had different activation effects on LfiMYB75.In conclusion,the results showed that LfiHY5 led to upregulate the transcription of LfiMYB75,and LfiMYB75 formed a complex with LfibHLH1,which increased the transcription level of LfiCHS and LfiANS to affect anthocyanin synthesis in crape myrtle.
文摘Idiopathic acute pancreatitis is a diagnostic challenge for gastroenterologists.The possibility of finding a cause for pancreatitis usually relies on how far the diagnostic study is taken.Endoscopic explorations such as endoscopic retrograde cholangiopancreatography and endoscopic ultrasonography can help to determine the cause of pancreatitis.Furthermore,microscopic bile examination and magnetic resonance cholangiopancreatography can also be helpful in the work up of these patients.In this article an approximation to the diagnostic approach to patients with idiopathic acute pancreatitis is made,taking into account the reported evidence with which to choose between the different available explorations.
文摘In this paper, the effect of adding different concentrations of kinetic inhibitors on the induction time of hydrogen sulfide hydrate formation in a reactor equipped with automatic adjustable temperature controller is studied. A novel method namely ＂sudden cooling＂ is used for performing the relevant measurements, in which the induction time of H2S hydrate in the presence/absence of PVP and L-tyrosine with different concentrations （100, 500, and 1000 ppm） is determined. As a result, PVP with the concentration of 1000 ppm in aqueous solution is detected as a more suitable material for increasing the induction time of H2S hydrate formation among the investigated kinetic hydrate inhibitors.
文摘A novel strategy, which is better-suited for preparing materials with a very microscopic structure, is described and the whisker-like composite of Co(OH) 2/HY was prepared by using this strategy. In addition, the mechanism by which the growth proceeds is not very rigorously worked out. Due to the high dispersed capability of HY towards to Co(OH) 2 resulting in loose whisker-like microstructure of Co(OH) 2, small channels become available for the diffusion of OH - electrolyte ions through all Co(OH) 2 thin layer. Consequentially, the prepared composite shows a very high specific capacitance (483 F/g) and utilization (93%) of effective electroactive composition of composite.
