The MODerate Resolution Imaging Spectroradiometer(MODIS)MCD43A products have been extensively applied in the remote sensing field,but recent researchers have demonstrated that these products still had the potential to...The MODerate Resolution Imaging Spectroradiometer(MODIS)MCD43A products have been extensively applied in the remote sensing field,but recent researchers have demonstrated that these products still had the potential to be further improved by using the latest development of the kernel-driven model[RossThick-LiSparseReciprocal-Snow(RTLSRS)]in snow-covered areas,since the MCD43A product algorithm[RossThick-LiSparseReciprocal(RTLSR)]needed to be improved for the accurate simulation of snow bidirectional reflectance distribution function(BRDF)signatures.In this paper,we proposed a practical approach to improve the MCD43A products,which used the Polarization and Directionality of the Earth's Reflectance(POLDER)observations and random forest algorithm to establish the relationship between the BRDF parameters(MCD43A1)estimated by the RTLSR and RTLSRS models.We applied this relationship to correct the MCD43A1 product and retrieve the corresponding albedo(MCD43A3)and nadir reflectance(MCD43A4).The results obtained highlight several aspects:(a)The proposed approach can perform well in correcting BRDF parameters[root mean square error(RMSE)=~0.04].(b)The corrected BRDF parameters were then used to retrieve snow albedo,which matched up quite well with the results of the RTLSRS model.(c)Finally,the snow albedo retrieved by the proposed approach was assessed using ground-based albedo observations.Results indicated that the retrieved snow albedo showed a higher accuracy as compared to the station measurements(RMSE=0.055,bias=0.005),which was better than the results of the MODIS albedo product(RMSE=0.064,bias=-0.018),especially at large angles.These results demonstrated that this proposed approach presented the potential to further improve the MCD43A products in snow-covered areas.展开更多
We present a theoretical study of the magnetic properties of the lanthanum copper manganate double perovskite La2CuMnO6 ceramic,using Monte Carlo simulations.We analyze and discuss the ground state phase diagrams in d...We present a theoretical study of the magnetic properties of the lanthanum copper manganate double perovskite La2CuMnO6 ceramic,using Monte Carlo simulations.We analyze and discuss the ground state phase diagrams in different planes to show the effect of every physical parameter.Based on the Monte Carlo simulations,which combine Metropolis algorithm and Ising model,we explore the thermal behavior of the total magnetization and susceptibility.We also present and discuss the influence of physical parameters such as the external magnetic field,the exchange coupling interactions between magnetic atoms,and the exchange magnetic field on the magnetization of the system.Moreover,the critical temperature of the system is about Tc=70 K,in agreement with the experimental value.Finally,the hysteresis loops of La2CuMnO6 are discussed.展开更多
We study the magnetic properties of the double perovskite ruthenate compound Sr2YRuO6 using Monte Carlo simulations(MCS).We elaborate the ground state phase diagrams for all possible and stable configurations.The magn...We study the magnetic properties of the double perovskite ruthenate compound Sr2YRuO6 using Monte Carlo simulations(MCS).We elaborate the ground state phase diagrams for all possible and stable configurations.The magnetizations and the susceptibilities as a function of temperature for the studied system are also reported.The effects of the exchange coupling interactions and the crystal field are examined and discussed.On the other hand, since the compound Sr2YRuO6 exhibits an antiferromagnetic behavior, we find its Néel temperature, TN≈ 31 K, which is in good agreement with the experimental results in the literature.To complete this study, the hysteresis loops and the coercive field as a function of the external magnetic field are also obtained for fixed values of the physical parameters.展开更多
聚集指数CI(Clumping Index)是植被冠层的一个重要结构参数,对植被冠层的辐射截获,以及全球碳、水循环的研究均有重要作用。现有星载CI产品的估算主要是基于CI-NDHD(Normalized Difference between Hotspot and Dark spot)线性模型方法...聚集指数CI(Clumping Index)是植被冠层的一个重要结构参数,对植被冠层的辐射截获,以及全球碳、水循环的研究均有重要作用。现有星载CI产品的估算主要是基于CI-NDHD(Normalized Difference between Hotspot and Dark spot)线性模型方法,由于针叶林和阔叶林在叶片尺度上存在聚集层级的差异,该模型对它们分别采用了不同的模型系数。但是,该模型对中粗分辨率的针阔混交林像元通常采用阔叶林的CI反演系数,因此,理论上会导致该类型CI的高估。为此,本文提出了一种动态选取混交林像元端元CI组分的方法,以改进针阔混交林植被聚集指数的估算精度。首先,通过国际地圈—生物圈计划(IGBP)的地表类型和描述二向性反射分布函数BRDF(Bidirectional Reflectance Distribution Function)特征的地表各向异性平整指数AFX(Anisotropic Flat Index)进行双重约束,逐像元地计算端元CI值;然后,结合高分辨率的土地覆盖分类数据确定端元在像元中的面积比例,并估算MODIS针阔混交林像元的聚集指数MFCI(Mixed Forest CI);最后,将方法应用于研究区MODIS数据的MFCI估算,并通过地面实测数据进行精度评价。结果表明:目前的MODIS产品算法高估了针阔混交林像元的CI值,而MFCI估算方法在CI-NDHD算法的基础上,可以较显著地改善该类型聚集指数的估算精度,当针叶林树种成数达到60%时,精度改善可达28.03%,其中,改进结果的均方根误差(RMSE)和偏差(Bias)各降低约84%和175%。研究表明,MFCI方法对针阔混合像元的端元组分的变化敏感,在高分辨率地表分类已知的条件下,MFCI方法为针阔混交林CI产品生产和精度提高提供了可行的解决方案。展开更多
目的:基于网络药理学与分子对接技术分析当归芍药散治疗卵巢癌(ovarian cancer)的药理机制。方法:结合文献和中药系统药理学数据库与分析平台(traditional Chinese medicine systems pharmacology database and analysis platform,TCMSP...目的:基于网络药理学与分子对接技术分析当归芍药散治疗卵巢癌(ovarian cancer)的药理机制。方法:结合文献和中药系统药理学数据库与分析平台(traditional Chinese medicine systems pharmacology database and analysis platform,TCMSP)对当归芍药散成分和作用靶点进行检索,将药物靶点和Genecards数据库所载卵巢癌靶标进行对比,结果输入STRING数据库,并在Cytoscape3.8.0软件中制作网络图。采用Rstudio软件进行基因本体(gene ontology,GO)功能富集分析、京都基因与基因组百科全书(Kyoto encyclopedia of genes and genomes,KEGG)通路富集分析。利用PyMOL软件对排名前5位的活性成分和核心靶标进行分子对接可视化分析。结果:筛选共得药物活性成分70个,涉及VEGFA、RELA、PTGS2、MMP9、TP53、JUN、PGR等98个作用靶标;GO功能富集分析、KEGG信号通路富集结果显示:当归芍药散治疗卵巢癌主要通过药物反应、RNA聚合酶Ⅱ启动子转录的正调控、雌二醇反应等调节磷酸酰肌醇3-激酶/蛋白激酶B(phosphatidylinositol 3-kinase-Akt signal transduction pathway/protein kinase B,PI3K/Akt)、丝裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK)、血管内皮生长因子(vascular endothelial growth factor,VEGF)等信号通路;分子对接结果表明黄芩素、鞣花酸与靶标蛋白有较好的结合活性。结论:当归芍药散治疗卵巢癌可能与VEGFA、TP53、PTGS2、PGR等作用靶标及调节PI3K-Akt、MAPK、VEGF等信号通路有关,黄芩素、鞣花酸可能是其发挥作用的主要成分。展开更多
内蒙古电网两项输变电工程荣获绿色建造水平三星评价,通过对获奖项目与其他绿色建造项目在策划、设计、施工、交付四个阶段实际情况的综合分析,指出了当前内蒙古电网工程绿色建造存在的未将绿色发展理念融入工程建造全过程、相关标准体...内蒙古电网两项输变电工程荣获绿色建造水平三星评价,通过对获奖项目与其他绿色建造项目在策划、设计、施工、交付四个阶段实际情况的综合分析,指出了当前内蒙古电网工程绿色建造存在的未将绿色发展理念融入工程建造全过程、相关标准体系及评价体系建设不完善等问题,从开展科学管理和应用建筑信息模型(Building Information Modeling,BIM)、大数据等方面提出了提高资源配置效率、提升建造整体水平的具体举措,以及进行绿色建造应用效果评估的主要参考指标及相应的评估方法,以促进绿色建造工作的深层次推进。展开更多
基金supported by the Fundamental Research Funds for the Central Universities(No.JZ2023HGQA0148)the National Natural Science Foundation of China(No.41971288).
文摘The MODerate Resolution Imaging Spectroradiometer(MODIS)MCD43A products have been extensively applied in the remote sensing field,but recent researchers have demonstrated that these products still had the potential to be further improved by using the latest development of the kernel-driven model[RossThick-LiSparseReciprocal-Snow(RTLSRS)]in snow-covered areas,since the MCD43A product algorithm[RossThick-LiSparseReciprocal(RTLSR)]needed to be improved for the accurate simulation of snow bidirectional reflectance distribution function(BRDF)signatures.In this paper,we proposed a practical approach to improve the MCD43A products,which used the Polarization and Directionality of the Earth's Reflectance(POLDER)observations and random forest algorithm to establish the relationship between the BRDF parameters(MCD43A1)estimated by the RTLSR and RTLSRS models.We applied this relationship to correct the MCD43A1 product and retrieve the corresponding albedo(MCD43A3)and nadir reflectance(MCD43A4).The results obtained highlight several aspects:(a)The proposed approach can perform well in correcting BRDF parameters[root mean square error(RMSE)=~0.04].(b)The corrected BRDF parameters were then used to retrieve snow albedo,which matched up quite well with the results of the RTLSRS model.(c)Finally,the snow albedo retrieved by the proposed approach was assessed using ground-based albedo observations.Results indicated that the retrieved snow albedo showed a higher accuracy as compared to the station measurements(RMSE=0.055,bias=0.005),which was better than the results of the MODIS albedo product(RMSE=0.064,bias=-0.018),especially at large angles.These results demonstrated that this proposed approach presented the potential to further improve the MCD43A products in snow-covered areas.
文摘We present a theoretical study of the magnetic properties of the lanthanum copper manganate double perovskite La2CuMnO6 ceramic,using Monte Carlo simulations.We analyze and discuss the ground state phase diagrams in different planes to show the effect of every physical parameter.Based on the Monte Carlo simulations,which combine Metropolis algorithm and Ising model,we explore the thermal behavior of the total magnetization and susceptibility.We also present and discuss the influence of physical parameters such as the external magnetic field,the exchange coupling interactions between magnetic atoms,and the exchange magnetic field on the magnetization of the system.Moreover,the critical temperature of the system is about Tc=70 K,in agreement with the experimental value.Finally,the hysteresis loops of La2CuMnO6 are discussed.
文摘We study the magnetic properties of the double perovskite ruthenate compound Sr2YRuO6 using Monte Carlo simulations(MCS).We elaborate the ground state phase diagrams for all possible and stable configurations.The magnetizations and the susceptibilities as a function of temperature for the studied system are also reported.The effects of the exchange coupling interactions and the crystal field are examined and discussed.On the other hand, since the compound Sr2YRuO6 exhibits an antiferromagnetic behavior, we find its Néel temperature, TN≈ 31 K, which is in good agreement with the experimental results in the literature.To complete this study, the hysteresis loops and the coercive field as a function of the external magnetic field are also obtained for fixed values of the physical parameters.
基金Natural Science Foundation of China （No.40871193） The Special Foundation for Free Exploration of State Laboratory of Remote Sensing Sci- ence （No.610ZY-06） Key Projects in the National Science ＆ Technology Pillar Program （No.2008BAC34B03）
文摘植被聚集指数(clumping index,CI(Ω))是表征植被冠层聚集程度的重要结构参数,由于其定量化研究起步较晚,导致对CI季相变化特征的研究不充分,结论争议较大.为此,本文基于长时间序列的MODIS CI产品,从北半球中高纬度植被物候特征敏感区,在13个国际地圈-生物圈计划(IGBP)类型中,优选了84个高质量的代表性像元,开展典型像元CI季相变化特征的案例研究.以归一化植被指数(normalized difference vegetation index,NDVI)作为对比,提出改进的动态阈值法,结合离散Fourier变换方法,分别提取不同地类的生长季开始时间(start of season,SOS)及生长季结束时间(end of season,EOS),最终建立北半球中高纬度各地类生长季与休眠期的经验Ω.结果表明:CI具有较为明显的物候变化规律及季节变化特征,甚至能够识别出耕地的一年两熟迹象,但相对于NDVI相对稳定的季相变化特征,大部分地类的CI表现出较大的变化和不确定性,其中,SOS和EOS多分别在第100和第300天左右变化,生长季则多维持在200d左右;提取物候特征参数的最佳阈值随提取时期、地物类别的变化而变化,其中提取SOS和EOS的最佳阈值多集中在40%~80%和80%~90%;经验Ω呈现出针叶林的聚集效应最强,耕地的聚集效应最弱的特征.本研究对于揭示不同地类CI季相特征及相关应用研究提供了有用的证据和参考.
文摘聚集指数CI(Clumping Index)是植被冠层的一个重要结构参数,对植被冠层的辐射截获,以及全球碳、水循环的研究均有重要作用。现有星载CI产品的估算主要是基于CI-NDHD(Normalized Difference between Hotspot and Dark spot)线性模型方法,由于针叶林和阔叶林在叶片尺度上存在聚集层级的差异,该模型对它们分别采用了不同的模型系数。但是,该模型对中粗分辨率的针阔混交林像元通常采用阔叶林的CI反演系数,因此,理论上会导致该类型CI的高估。为此,本文提出了一种动态选取混交林像元端元CI组分的方法,以改进针阔混交林植被聚集指数的估算精度。首先,通过国际地圈—生物圈计划(IGBP)的地表类型和描述二向性反射分布函数BRDF(Bidirectional Reflectance Distribution Function)特征的地表各向异性平整指数AFX(Anisotropic Flat Index)进行双重约束,逐像元地计算端元CI值;然后,结合高分辨率的土地覆盖分类数据确定端元在像元中的面积比例,并估算MODIS针阔混交林像元的聚集指数MFCI(Mixed Forest CI);最后,将方法应用于研究区MODIS数据的MFCI估算,并通过地面实测数据进行精度评价。结果表明:目前的MODIS产品算法高估了针阔混交林像元的CI值,而MFCI估算方法在CI-NDHD算法的基础上,可以较显著地改善该类型聚集指数的估算精度,当针叶林树种成数达到60%时,精度改善可达28.03%,其中,改进结果的均方根误差(RMSE)和偏差(Bias)各降低约84%和175%。研究表明,MFCI方法对针阔混合像元的端元组分的变化敏感,在高分辨率地表分类已知的条件下,MFCI方法为针阔混交林CI产品生产和精度提高提供了可行的解决方案。
基金Foundation： National Natural Science Foundation of China （No.41171261, 40871193） National Basic Research Program of China （973 Program） （No. 2013CB733401）志谢本文中使用的POLDER-3/ARASOLBRDF数据由法国气候与环境科学实验室（LSCE）生产,并由POSTEL服务中心提供,在此表示衷心的感谢!
文摘目的:基于网络药理学与分子对接技术分析当归芍药散治疗卵巢癌(ovarian cancer)的药理机制。方法:结合文献和中药系统药理学数据库与分析平台(traditional Chinese medicine systems pharmacology database and analysis platform,TCMSP)对当归芍药散成分和作用靶点进行检索,将药物靶点和Genecards数据库所载卵巢癌靶标进行对比,结果输入STRING数据库,并在Cytoscape3.8.0软件中制作网络图。采用Rstudio软件进行基因本体(gene ontology,GO)功能富集分析、京都基因与基因组百科全书(Kyoto encyclopedia of genes and genomes,KEGG)通路富集分析。利用PyMOL软件对排名前5位的活性成分和核心靶标进行分子对接可视化分析。结果:筛选共得药物活性成分70个,涉及VEGFA、RELA、PTGS2、MMP9、TP53、JUN、PGR等98个作用靶标;GO功能富集分析、KEGG信号通路富集结果显示:当归芍药散治疗卵巢癌主要通过药物反应、RNA聚合酶Ⅱ启动子转录的正调控、雌二醇反应等调节磷酸酰肌醇3-激酶/蛋白激酶B(phosphatidylinositol 3-kinase-Akt signal transduction pathway/protein kinase B,PI3K/Akt)、丝裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK)、血管内皮生长因子(vascular endothelial growth factor,VEGF)等信号通路;分子对接结果表明黄芩素、鞣花酸与靶标蛋白有较好的结合活性。结论:当归芍药散治疗卵巢癌可能与VEGFA、TP53、PTGS2、PGR等作用靶标及调节PI3K-Akt、MAPK、VEGF等信号通路有关,黄芩素、鞣花酸可能是其发挥作用的主要成分。
文摘内蒙古电网两项输变电工程荣获绿色建造水平三星评价,通过对获奖项目与其他绿色建造项目在策划、设计、施工、交付四个阶段实际情况的综合分析,指出了当前内蒙古电网工程绿色建造存在的未将绿色发展理念融入工程建造全过程、相关标准体系及评价体系建设不完善等问题,从开展科学管理和应用建筑信息模型(Building Information Modeling,BIM)、大数据等方面提出了提高资源配置效率、提升建造整体水平的具体举措,以及进行绿色建造应用效果评估的主要参考指标及相应的评估方法,以促进绿色建造工作的深层次推进。
