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Analysis of vegetation response to rainfall with satellite images in Dongting Lake

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Journal of Geographical Sciences 2011年第1期21卷 135-149页

作者： JIANG Weiguo HOU Peng ZHU Xiaohua cao guangzhen LIU Xiaoman cao Ruyin State Key Laboratory of Earth Process and Resource Ecology Beijing Normal University Beijing 100875 China Academy of Disaster Reduction and Emergency Management Beijing Normal University Beijing100875 China Satellite Environment Center MEP Beijing 100094 China Institute of Geographic Sciences and Natural Resources Research CAS Beijing 100101 China Institute of Geographic Sciences and Natural Resources Research CAS Beijing 100101 China Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites China Meteorological Administration Beijing 100081 China

We analyzed the Normalized Difference Vegetation Index （NDVI） from satellite images and precipitation data from meteorological stations from 1998 to 2007 in the Dongting Lake wetland watershed to better understand the eco-hydrological effect of atmospheric precipitation and its relationship with vegetation. First,we analyzed its general spatio-temporal distribution using its mean,standard deviation and linear trend. Then,we used the Empirical Orthogonal Functions （EOF） method to decompose the NDVI and precipitation data into spatial and temporal modes. We selected four leading modes based on North and Scree test rules and analyzed the synchronous seasonal and inter-annual variability between the vegetation index and precipitation,distinguishing time-lagged correlations between EOF modes with the correlative degree analysis method. According to our detailed analyses,the vegetation index and precipitation exhibit a prominent correlation in spatial distribution and seasonal variation. At the 90% confidence level,the time lag is around 110 to 140 days,which matches well with the seasonal variation.

关键词： eco-hydrology precipitation vegetation remote sensing wetland Dongting Lake

Sensitivity analyses of different vegetations responding to climate change in inland river basin of China

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Journal of Geographical Sciences 2012年第3期22卷 387-406页

作者： Hou Peng Wang Qiao cao guangzhen Wang Changzuo Zhan Zhiming Yang Bingfeng Satellite Environment Application Center Ministry of Environmental Protection Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites China Meteorological Administration School of Architecture Tsinghua University

Terrestrial ecosystem and climate system are closely related to each other. Faced with the unavoidable global climate change, it is important to investigate terrestrial ecosystem responding to climate change. In inland river basin of arid and semi-arid regions in China, sensitivity difference of vegetation responding to climate change from 1998 to 2007 was analyzed in this paper. （1） Differences in the global spatio-temporal distribution of vegetation and climate are obvious. The vegetation change shows a slight degradation in this whole region. Degradation is more obvious in densely vegetated areas. Temperature shows a general downward trend with a linear trend coefficient of -1.1467. Conversely, precipitation shows an increasing trend with a linear trend coefficient of 0.3896. （2） About the central tendency response, there are similar features in spatial distribution of both NDVI responding to precipitation （NDVI-P） and NDVI responding to AI （NDVI-AI）, which are contrary to that of NDVI responding to air temperature （NDVI-T）. Typical sensitivity region of NDVI-P and NDVI-AI mainly covers the northern temperate arid steppe and the northern temperate desert steppe. NDVI-T typical sensitivity region mainly covers the northern temperate desert steppe. （3） Regarding the fluctuation amplitude response, NDVI-T is dominated by the lower sensitivity, typical regions of the warm temperate shrubby, selui-shrubby, bare extreme dry desert, and northern temperate meadow steppe in the east and temperate semi-shrubby, dwarf arboreous desert in the north are high response. （4） Fluctuation amplitude responses between NDVI-P and NDVI-AI present a similar spatial distribution. The typical sensitivity region mainly covers the northern temperate desert steppe. There are various linear change trend responses of NDVI-T, NDVI-P and NDVI-AI. As to the NDVI-T and NDVI-AI, which are influenced by the boundary effect of semi-arid and semi-humid climate zones, there is less correlation of thei

关键词： vegetation climate satellite images sensitivity analyses inland river basin China

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精芪饮料提取工艺优化

中药与临床 2024年第3期15卷 30-35页

作者：刘希贤张丝怡杨耀松曹光珍何晴宋欣鲜彭腾龙飞冯光富成都中医药大学药学院四川成都611137 四川省骨科医院四川成都610041

目的:优化精芪饮料的提取工艺。方法:以总多糖得率和干膏率为指标,利用单因素和正交实验探索精芪饮料的提取工艺,其中因素包括提取时间、料液比及提取次数。结果:精芪饮料的最佳提取时间为2.5 h,提取次数为3次,提取料液比为1∶10。最佳... 详细信息

目的:优化精芪饮料的提取工艺。方法:以总多糖得率和干膏率为指标,利用单因素和正交实验探索精芪饮料的提取工艺,其中因素包括提取时间、料液比及提取次数。结果:精芪饮料的最佳提取时间为2.5 h,提取次数为3次,提取料液比为1∶10。最佳提取工艺的总多糖得率为3.59%,干膏率为58.36%,RSD为1.31%。结论:正交实验法可用于精芪饮料的提取,经过验证实验证明该工艺稳定可行,可用于大工业的生产。

关键词：二精丸当归补血汤提取工艺研究药食同源

Developing the Science Product Algorithm Testbed for Chinese Next-Generation Geostationary Meteorological Satellites：Fengyun-4 Series

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Journal of Meteorological Research 2017年第4期31卷 708-719页

作者： Min MIN Chunqiang WU Chuan LI Hui LIU Na XU Xiao WU Lin CHEN Fu WANG Fenglin SUN Danyu QIN Xi WANG Bo LI Zhaojun ZHENG guangzhen cao Lixin DONG Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites National Satellite Meteorological Center China Meteorological Administration Beijing 100081

Fengyun-4A（FY-4A）, the first of the Chinese next-generation geostationary meteorological satellites, launched in2016, offers several advances over the FY-2： more spectral bands, faster imaging, and infrared hyperspectral measurements. To support the major objective of developing the prototypes of FY-4 science algorithms, two science product algorithm testbeds for imagers and sounders have been developed by the scientists in the FY-4 Algorithm Working Group（AWG）. Both testbeds, written in FORTRAN and C programming languages for Linux or UNIX systems, have been tested successfully by using Intel/g compilers. Some important FY-4 science products, including cloud mask, cloud properties, and temperature profiles, have been retrieved successfully through using a proxy imager, Himawari-8/Advanced Himawari Imager（AHI）, and sounder data, obtained from the Atmospheric Infra Red Sounder, thus demonstrating their robustness. In addition, in early 2016, the FY-4 AWG was developed based on the imager testbed—a near real-time processing system for Himawari-8/AHI data for use by Chinese weather ***, robust and flexible science product algorithm testbeds have provided essential and productive tools for popularizing FY-4 data and developing substantial improvements in FY-4 products.

关键词： geostationary meteorological satellite FY-4 algorithm testbed cloud properties

陆表比辐射率对遥感陆表温度反演结果的影响分析

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遥感技术与应用 2023年第4期38卷 835-841页

作者：曹广真闵敏侯鹏中国气象局中国遥感卫星辐射测量和定标重点开放实验室许健民气象卫星创新中心国家卫星气象中心北京100081 中山大学大气科学学院广东珠江519082 环境保护部卫星环境应用中心国家环境保护卫星遥感重点实验室北京100094

陆表比辐射率(Land Surface Emissivity,LSE)是衡量物体表面以热辐射形式释放能量相对强弱能力的物理量,是影响遥感陆表温度(Land Surface Temperature,LST)的重要基本参数之一。为了分析不同条件下LSE对遥感LST反演结果的影响,基于Hima... 详细信息

陆表比辐射率(Land Surface Emissivity,LSE)是衡量物体表面以热辐射形式释放能量相对强弱能力的物理量,是影响遥感陆表温度(Land Surface Temperature,LST)的重要基本参数之一。为了分析不同条件下LSE对遥感LST反演结果的影响,基于Himawari8AHI(Advanced Himawari Imager,AHI)的分裂窗通道热红外遥感数据,采用Wan及Dozier的分裂窗算法,研究陆表温度反演结果对LSE的敏感性。首先,对LSE产品分别加入不同均值和标准差的高斯噪声,以此代表LSE不同的误差水平;然后,在其他条件不变的情况下,将带不同噪声的LSE和不带噪声的LSE分别输入分裂窗算法进行LST的反演;最后,分析不同时间、不同水汽、不同观测角度和不同下垫面条件下,LSE对LST的影响。结果表明:(1)无论白天、夜间还是日均LST,输入添加噪声的LSE较输入原始的LSE反演所得的LST数值总体略低,而且随着所添加噪声标准差的增大,所得LST差值的标准差增大。当LSE的噪声标准差为0.01时,所得白天、夜间和日均LST差值的标准差分别为0.48 K、0.52 K和0.34 K;而当LSE的噪声标准差为0.03时,所得LST差值的标准差则分别升高到1.46 K、1.57 K和0.88 K。(2)不管水汽和观测角度条件如何,总体上,输入添加噪声的与输入原始LSE反演所得的LST相关系数随着所加噪声标准差的增大而减小,均方根误差和标准差则随着所加噪声标准差的增大而增大,偏差为负值,其绝对值随所加噪声标准差的增大而减小。(3)对于不同的下垫面,随着所加噪声标准差的增大,LSE添加噪声与不添加噪声反演所得的LST差值的标准差增大,当所加噪声标准差为0.01时,多树草原、开放灌木和草原LST差值的标准差分别为0.52 K、0.51 K和0.53 K。而当所加噪声标准差为0.03时,三者LST差值的标准差分别升高到1.58 K、1.53 K和1.6 K。

关键词：陆表比辐射率陆表温度高斯分布噪声分裂窗算法

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北京市城市化对地表温度时空特征的影响

气象 2010年第3期36卷 19-26页

作者：曹广真侯鹏毛显强中国气象局中国遥感卫星辐射测量和定标重点开放实验室国家卫星气象中心北京100081 北京师范大学资源学院北京100875 北京师范大学环境学院北京100875

分别采用常规气象数据和遥感资料,结合城市化发展总体水平不同的三大板块,分析北京市城市化对地表温度时空变化特征的影响。(1)将北京市1978—2006年常规气象站点的陆表温度(Land Surface Temperature,LST)观测资料与三大板块结合,分析... 详细信息

分别采用常规气象数据和遥感资料,结合城市化发展总体水平不同的三大板块,分析北京市城市化对地表温度时空变化特征的影响。(1)将北京市1978—2006年常规气象站点的陆表温度(Land Surface Temperature,LST)观测资料与三大板块结合,分析城市化对LST年、季、白天、夜间、最大值和最小值的影响。发现1978—2006年期间,北京市三大板块LST均值总体上均呈上升趋势,且大多数情况下,第一板块的>第二板块的>第三板块的。(2)采用北京市2001年和2006年全年的EOS MODIS MOD 13归一化植被指数(Normalized Difference Vegetation Index,NDVI)产品以及MOD11白天/夜间LST产品,分析城市化过程中下垫面变化对LST的影响。总体上,北京市2006年较2001年NDVI减少的比例为51.3%,白天LST升高的比例为73.74%,夜间LST升高的比例高达90.92%。(3)北京市2006年与2001年NDVI的差值以及白天、夜间LST的差值的联合分类结果表明,第一和第二板块均表现出2006年较2001年NDVI减少、白天LST增加的类别所占的百分比最大,分别占54.29%和40.95%,而且均大于其在第三板块中所占的比例34%,而三个板块中NDVI增加、白天LST减少的百分比与NDVI减少、白天LST增加的百分比之和均超过了50%。第一、第二和第三板块中2006年较2001年NDVI减少、夜间LST增加的类别所占百分比分别为51.67%、44.2%和42.46%。这些数据定量地说明了城市化过程中下垫面变化对白天、夜间LST的影响。

关键词：城市化地表温度常规气象数据遥感资料

Zeros of Complete Symmetric Polynomials over Finite Fields

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Journal of Systems Science & Complexity 2024年第4期37卷 1772-1788页

作者： cao Wei School of Mathematics and Statistics Minnan Normal UniversityZhangzhou 363000China

Wan and Zhang(2021) obtained a nontrivial lower bound for the number of zeros of complete symmetric polynomials over finite fields,and proposed a problem whether their bound can be *** this paper,the author improves Wan-Zhang's bound from three *** proposed results are based on the estimates related to the number of certain permutations and the value sets of non-permutation polynomials associated to the complete symmetric *** the author believes that there are still possibilities to improve the bounds and hence Wan-Zhang's bound.

关键词： Complete symmetric polynomial finite field permutation polynomial value set

Pt nanodendrites with a PtIr alloy surface structure exhibit excellent stability toward acidic hydrogen evolution reaction

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Nano Research 2024年第6期17卷 4844-4849页

作者： Chang Liu Zongnan Wei Minna cao Rong cao State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China University of Chinese Academy of Sciences Beijing 100049China Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350108China

The development of effective and stable electrocatalysts for the hydrogen evolution reaction(HER)in acidic electrolytes is a significant *** this work,homogeneous Pt nanodendrites(Pt NDs)with a PtIr shell were successfully synthesized by a two-step wet chemical *** open three-dimensional(3D)dendritic structure exhibited exceptional electrocatalytic characteristics,exposing as many active sites as ***,by alloying Ir with Pt on the surface,catalytic activity was greatly enhanced while ensuring extremely high *** surface-enriched platinum nanodendritic catalysts(Pt@PtIr NDs)outperformed the control samples and the commercial *** acidic HER test,Pt@PtIr NDs had a lower overpotential(22 mV)than Pt NDs(26 mV)and commercial Pt/C(31 mV)at 10 mA/cm^(2),and the activity of Pt@PtIr NDs remained consistent even after undergoing a continuous durability test for at least 168 h,which was much superior to the performance of commercial Pt/C(10 h)under identical test *** study revealed that the application of 3D Pt dendritic metal alloys may offer a chance for the development of enhanced electrocatalysts in acidic HER.

关键词： Pt nanodendrites iridium high stability hydrogen evolution reaction alloy

Quantitative phase imaging based on holography:trends and new perspectives

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Light(Science & Applications) 2024年第7期13卷 1235-1277页

作者： Zhengzhong Huang Liangcai cao Department of Precision Instrument Tsinghua UniversityBeijing 100084China

In 1948,Dennis Gabor proposed the concept of holography,providing a pioneering solution to a quantitative description of the optical *** 75 years of development,holographic imaging has become a powerful tool for optical wavefront measurement and quantitative phase *** emergence of this technology has given fresh energy to physics,biology,and materials *** holography(DH)possesses the quantitative advantages of wide-field,non-contact,precise,and dynamic measurement capability for *** has unique capabilities for the propagation of optical fields by measuring light scattering with phase *** offers quantitative visualization of the refractive index and thickness distribution of weak absorption samples,which plays a vital role in the pathophysiology of various diseases and the characterization of various *** provides a possibility to bridge the gap between the imaging and scattering *** propagation of wavefront is described by the complex *** complex-value in the complex-domain is reconstructed from the intensityvalue measurement by camera in the ***,we regard the process of holographic recording and reconstruction as a transformation between complex-domain and real-domain,and discuss the mathematics and physical principles of *** review the DH in underlying principles,technical approaches,and the breadth of *** conclude with emerging challenges and opportunities based on combining holographic imaging with other methodologies that expand the scope and utility of holographic imaging even *** multidisciplinary nature brings technology and application experts together in label-free cell biology,analytical chemistry,clinical sciences,wavefront sensing,and semiconductor production.

关键词： holographic phase precise