水稻穗颈瘟作为稻瘟病的一种发病形式常以褐色斑点性状出现在水稻穗颈节部位,对稻穗颈瘟病害快速、无损的识别与分级评估一直是备受关注的研究课题。该研究以高寒地区粳稻大田试验为基础,利用无人机高光谱平台获取不同病害等级的水稻穗...水稻穗颈瘟作为稻瘟病的一种发病形式常以褐色斑点性状出现在水稻穗颈节部位,对稻穗颈瘟病害快速、无损的识别与分级评估一直是备受关注的研究课题。该研究以高寒地区粳稻大田试验为基础,利用无人机高光谱平台获取不同病害等级的水稻穗颈瘟冠层数据;分别以不同处理的光谱数据作为输入量,使用随机森林(Random Forest,RF)的方法进行建模,并结合水稻生理对各输入量的特征关联加以解释。结果表明:随着穗颈瘟病害等级的提升,水稻冠层反射率整体呈现下降的趋势;植被指数组合(Combination of Vegetation Indices,CVIs)作为输入量建立起来的预测模型具有最高的精度,预测集精度达到90%,Kappa系数为0.86,能够解释穗颈瘟所引起的植株整体生理参数综合变化过程。该研究结果可为无人机高光谱遥感实现穗颈瘟病定量遥感监测与预警分级提供支持。展开更多
Landfill leachates with different ages （mature leachate, 11 years; semi-mature leachate, 5 years; fresh leachate, under operation） were collected from Laogang Refuse Landfill, Shanghai to characterize the colloid si...Landfill leachates with different ages （mature leachate, 11 years; semi-mature leachate, 5 years; fresh leachate, under operation） were collected from Laogang Refuse Landfill, Shanghai to characterize the colloid size distribution and variations of leachate. These leachates were separated using micro-filtration and ultra-filtration into specific size fractions, i.e., suspended particles （SP） （〉 1.2 μm）, coarse colloids （CC） （1.2-0.45 μm）, fine colloids （FC） （0.45 m, 5 kDa/1 kDa molecular weight （MW））, and dissolved organic matters （DM, 〈 5 kDa/1 kDa MW）. The specific colloids in each size fraction were quantified and characterized through chemical oxygen demands （COD）, total solid （TS）, pH, NH4^＋-N, total organic carbon （TOC） and fixed solid （FS）. It was found that COD, NH^4＋-N and TS in leachate decreased significantly over ages, while pH increased. The dissolved fractions （〈 5 kDa/1 kDa） dominated （over 50%） in three leachates in terms of COD, and the organic matter content in dissolved fraction of leachates decreased and the inorganic matter increased as the disposal time extended, with the TOC/COD ratio 30%-7%. Dissolved fractions decreased from 82% to 40% in terms of TOC as the disposal time extended, suggested that the organic matter remained in leachate would form into middle molecular weight substances during the degradation process.展开更多
Quantum networks provide opportunities and challenges across a range of intellectual and technical frontiers,including quantum computation,communication,and others.Unlike traditional communication networks,quantum net...Quantum networks provide opportunities and challenges across a range of intellectual and technical frontiers,including quantum computation,communication,and others.Unlike traditional communication networks,quantum networks utilize quantum bits rather than classical bits to store and transmit information.Quantum key distribution(QKD)relying on the principles of quantum mechanics is a key component in quantum networks and enables two parties to produce a shared random secret key,thereby ensuring the security of data transmission.In this work,we propose a cost-effective quantum downstream access network structure in which each user can get their corresponding key information through terminal distribution.Based on this structure,we demonstrate the first four-end-users quantum downstream access network in continuous variable QKD with a local local oscillator.In contrast to point-to-point continuous variable QKD,the network architecture reevaluates the security of each user and accounts for it accordingly,and each user has a lower tolerance for excess noise as the overall network expands with more users.Hence,the feasibility of the experiment is based on the analysis of the theoretical model,noise analysis,and multiple techniques such as the particle filter and adaptive equalization algorithm used to suppress excess noise.The results show that each user can get a low level of excess noise and can achieve secret key rates of 546 kbps,535 kbps,522.5 kbps,and 512.5 kbps under a transmission distance of 10 km,respectively,with the finite-size block of 1×10~8.This not only verifies the good performance but also provides the foundation for the future multi-user quantum downstream access networks.展开更多
Cavity-enhanced single quantum dots(QDs)are the main approach towards ultra-high-performance solid-state quantum light sources for scalable photonic quantum technologies.Nevertheless,harnessing the Purcell effect requ...Cavity-enhanced single quantum dots(QDs)are the main approach towards ultra-high-performance solid-state quantum light sources for scalable photonic quantum technologies.Nevertheless,harnessing the Purcell effect requires precise spectral and spatial alignment of the QDs’emission with the cavity mode,which is challenging for most cavities.Here we have successfully integrated miniaturized Fabry-Perot microcavities with a piezoelectric actuator,and demonstrated a bright single-photon source derived from a deterministically coupled QD within this microcavity.Leveraging the cavity-membrane structures,we have achieved large spectral tunability via strain tuning.On resonance,a high Purcell factor of~9 is attained.The source delivers single photons with simultaneous high extraction efficiency of 0.58,high purity of 0.956(2)and high indistinguishability of 0.922(4).Together with its compact footprint,our scheme facilitates the scalable integration of indistinguishable quantum light sources on-chip,therefore removing a major barrier to the development of solid-state quantum information platforms based on QDs.展开更多
文摘水稻穗颈瘟作为稻瘟病的一种发病形式常以褐色斑点性状出现在水稻穗颈节部位,对稻穗颈瘟病害快速、无损的识别与分级评估一直是备受关注的研究课题。该研究以高寒地区粳稻大田试验为基础,利用无人机高光谱平台获取不同病害等级的水稻穗颈瘟冠层数据;分别以不同处理的光谱数据作为输入量,使用随机森林(Random Forest,RF)的方法进行建模,并结合水稻生理对各输入量的特征关联加以解释。结果表明:随着穗颈瘟病害等级的提升,水稻冠层反射率整体呈现下降的趋势;植被指数组合(Combination of Vegetation Indices,CVIs)作为输入量建立起来的预测模型具有最高的精度,预测集精度达到90%,Kappa系数为0.86,能够解释穗颈瘟所引起的植株整体生理参数综合变化过程。该研究结果可为无人机高光谱遥感实现穗颈瘟病定量遥感监测与预警分级提供支持。
基金supported by the State Key Laboratory of Pollution Control and Resource Reuse Foundation(No.PCRRF09008)the Key Project of Science and Technology Commission of Shanghai Municipality (No.08Dz1202800)
文摘Landfill leachates with different ages （mature leachate, 11 years; semi-mature leachate, 5 years; fresh leachate, under operation） were collected from Laogang Refuse Landfill, Shanghai to characterize the colloid size distribution and variations of leachate. These leachates were separated using micro-filtration and ultra-filtration into specific size fractions, i.e., suspended particles （SP） （〉 1.2 μm）, coarse colloids （CC） （1.2-0.45 μm）, fine colloids （FC） （0.45 m, 5 kDa/1 kDa molecular weight （MW））, and dissolved organic matters （DM, 〈 5 kDa/1 kDa MW）. The specific colloids in each size fraction were quantified and characterized through chemical oxygen demands （COD）, total solid （TS）, pH, NH4^＋-N, total organic carbon （TOC） and fixed solid （FS）. It was found that COD, NH^4＋-N and TS in leachate decreased significantly over ages, while pH increased. The dissolved fractions （〈 5 kDa/1 kDa） dominated （over 50%） in three leachates in terms of COD, and the organic matter content in dissolved fraction of leachates decreased and the inorganic matter increased as the disposal time extended, with the TOC/COD ratio 30%-7%. Dissolved fractions decreased from 82% to 40% in terms of TOC as the disposal time extended, suggested that the organic matter remained in leachate would form into middle molecular weight substances during the degradation process.
基金National Natural Science Foundation of China(62371060,62001041,62201012)State Key Laboratory of Information Photonics and Optical Communications(IPOC2022ZT09).
文摘Quantum networks provide opportunities and challenges across a range of intellectual and technical frontiers,including quantum computation,communication,and others.Unlike traditional communication networks,quantum networks utilize quantum bits rather than classical bits to store and transmit information.Quantum key distribution(QKD)relying on the principles of quantum mechanics is a key component in quantum networks and enables two parties to produce a shared random secret key,thereby ensuring the security of data transmission.In this work,we propose a cost-effective quantum downstream access network structure in which each user can get their corresponding key information through terminal distribution.Based on this structure,we demonstrate the first four-end-users quantum downstream access network in continuous variable QKD with a local local oscillator.In contrast to point-to-point continuous variable QKD,the network architecture reevaluates the security of each user and accounts for it accordingly,and each user has a lower tolerance for excess noise as the overall network expands with more users.Hence,the feasibility of the experiment is based on the analysis of the theoretical model,noise analysis,and multiple techniques such as the particle filter and adaptive equalization algorithm used to suppress excess noise.The results show that each user can get a low level of excess noise and can achieve secret key rates of 546 kbps,535 kbps,522.5 kbps,and 512.5 kbps under a transmission distance of 10 km,respectively,with the finite-size block of 1×10~8.This not only verifies the good performance but also provides the foundation for the future multi-user quantum downstream access networks.
基金We acknowledge Jin Liu and Yu-Ming He for the valuable discussions.We are grateful for financial support from the Science and Technology Program of Guangzhou(202103030001)the Innovation Program for Quantum Science and Technology(2021ZD0301400,2021ZD0301605)+4 种基金the National Key R&D Program of Guang-dong Province(2020B0303020001)the National Natural Science Foundation of China(12074442,12074433,12174447)the Natural Science Foundation of Hunan Province(2021JJ20051)the science and technology innovation Program of Hunan Province(2021RC3084)the research program of national university of defense technology(ZK21-01,22-ZZCX-067).
文摘Cavity-enhanced single quantum dots(QDs)are the main approach towards ultra-high-performance solid-state quantum light sources for scalable photonic quantum technologies.Nevertheless,harnessing the Purcell effect requires precise spectral and spatial alignment of the QDs’emission with the cavity mode,which is challenging for most cavities.Here we have successfully integrated miniaturized Fabry-Perot microcavities with a piezoelectric actuator,and demonstrated a bright single-photon source derived from a deterministically coupled QD within this microcavity.Leveraging the cavity-membrane structures,we have achieved large spectral tunability via strain tuning.On resonance,a high Purcell factor of~9 is attained.The source delivers single photons with simultaneous high extraction efficiency of 0.58,high purity of 0.956(2)and high indistinguishability of 0.922(4).Together with its compact footprint,our scheme facilitates the scalable integration of indistinguishable quantum light sources on-chip,therefore removing a major barrier to the development of solid-state quantum information platforms based on QDs.
