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Threshold of climate extremes that impact vegetation productivity over the Tibetan Plateau

Science China Earth Sciences 2024年第6期67卷 1967-1977页

作者： Zhenggang PIAO xiangyi li Hao XU Kai WANG Shuchang TANG Fei KAN Songbai HONG College of Urban and Environmental Sciences Peking UniversityBeijing 100871China

Vegetation growth is adversely impacted by multiple climate extremes related to the water and thermal stress over the Tibetan Plateau(TP).However,it remains unknown at which stress level these climate extremes can trigger the abrupt shifts of vegetation response to climate extremes and result in the maximum vegetation response across TP.To fill this knowledge gap,we combined the hydrometeorological data and the satellite-derived vegetation index to detect two critical thresholds that determine the response of vegetation productivity to droughts,high-temperature extremes,and low-temperature extremes,respectively,during 2001-2018.Our results show that the response of vegetation productivity to droughts rapidly increases once crossing -1.41±0.6 standard deviation(σ)below the normal conditions of soil moisture.When crossing-2.98σ±0.9σ,vegetation productivity is maximum damaged by droughts.High-temperature extremes,which have the two thresholds of 1.34σ±0.4σand 2.31σ±0.4σover TP,are suggested to trigger the strong response of vegetation productivity at a milder stress level than low-temperature extremes(two thresholds:-1.44σ±0.5σand-2.53σ±0.8σ).Moreover,we found the compounded effects of soil moisture deficit in reducing the threshold values of both high-and low-temperature extremes.Based on the derived thresholds of climate extremes that impact vegetation productivity,Earth System Models project that southwestern TP and part of the northeastern TP will become the hotspots with a high exposure risk to climate extremes by 2100.This study deciphers the high-impact extreme climates using two important thresholds across TP,which advances the understanding of the vegetation response to different climate extremes and provides a paradigm for assessing the impacts of climate extremes on regional ecosystems.

关键词： Tibetan Plateau Climate extremes Thresholds Vegetation productivity

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Federated Edge Learning for the Wireless Physical Layer:Opportunities and Challenges

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China Communications 2022年第8期19卷 15-30页

作者： Yiming Cui Jiajia Guo xiangyi li Le liang Shi Jin National Mobile Communications Research Laboratory and Frontiers Science Center for Mobile Information Communication and Security Southeast UniversityNanjing 210096China Purple Mountain Laboratories Nanjing 211111China

Deep learning(DL)has been applied to the physical layer of wireless communication systems,which directly extracts environment knowledge from data and outperforms conventional methods either in accuracy or computation complexity.However,most related research works employ centralized training that inevitably involves collecting training data from edge devices.The data uploading process usually results in excessive communication overhead and privacy disclosure.Alternatively,a distributed learning approach named federated edge learning(FEEL)is introduced to physical layer designs.In FEEL,all devices collaborate to train a global model only by exchanging parameters with a nearby access point.Because all datasets are kept local,data privacy is better protected and data transmission overhead can be reduced.This paper reviews the studies on applying FEEL to the wireless physical layer including channel state information acquisition,transmitter,and receiver design,which represent a paradigm shift of the DL-based physical layer design.In the meantime they also reveal several limitations inherent in FEEL,particularly when applied to the wireless physical layer,thus motivating further research efforts in the field.

关键词： deep learning federated edge learning wireless communication physical layer

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Global variations in critical drought thresholds that impact vegetation

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National Science Review 2023年第5期10卷 180-193页

作者： xiangyi li Shilong Piao Chris Huntingford Josep Pe?uelas Hui Yang Hao Xu Anping Chen Pierre Friedlingstein Trevor F.Keenan Stephen Sitch Xuhui Wang Jakob Zscheischler Miguel D.Mahecha Laboratoire de Météorologie Dynamique Institut Pierre-Simon LaplaceCNRS-ENS-UPMC-XDépartement de GeósciencesEcole Normale Superieure Earth and Environmental Sciences Area Lawrence Berkeley National Laboratory Department of Environmental Science Policy&ManagementUniversity of California Berkeley Department of Geography College of Life and Environmental SciencesUniversity of Exeter Department of Computational Hydrosystems Helmholtz Centre for Environmental Research—Ufz Remote Sensing Centre for Earth System Research Leipzig University Sino-French Institute for Earth System Science College of Urban and Environmental SciencesPeking University Key Laboratory of Alpine Ecology and Biodiversity Institute of Tibetan Plateau ResearchCenter for Excellence in Tibetan Earth ScienceChinese Academy of Sciences UK Centre for Ecology and Hydrology CSIC Global Ecology Unit CREAF-CSIC-UAB CREAF Cerdanyola de Vallès Department of Biogeochemical Integration Max Planck Institute for Biogeochemistry Department of Biology Colorado State University Graduate Degree Program in Ecology Colorado State University Department of Mathematics College of Engineering Mathematics and Physical SciencesUniversity of Exeter

Identifying the thresholds of drought that,if crossed,suppress vegetation functioning is vital for accurate quantification of how land ecosystems respond to climate variability and change.We present a globally applicable framework to identify drought thresholds for vegetation responses to different levels of known soil-moisture deficits using four remotely sensed vegetation proxies spanning 2001-2018.The thresholds identified represent critical inflection points for changing vegetation responses from highly resistant to highly vulnerable in response to drought stress,and as a warning signal for substantial vegetation impacts.Drought thresholds varied geographically,with much lower percentiles of soil-moisture anomalies in vegetated areas covered by more forests,corresponding to a comparably stronger capacity to mitigate soil water deficit stress in forested ecosystems.Generally,those lower thresholds are detected in more humid climates.State-of-the-art land models,however,overestimated thresholds of soil moisture(i.***.overestimating drought impacts),especially in more humid areas with higher forest covers and arid areas with few forest covers.Based on climate model projections,we predict that the risk of vegetation damage will increase by the end of the twenty-first century in some hotspots like East Asia,Europe,Amazon,southern Australia and eastern and southern Africa.Our data-based results will inform projections on future drought impacts on terrestrial ecosystems and provide an effective tool for drought management.

关键词： drought threshold inflection points vegetation response soil moisture drought impacts

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基于共形几何代数的并联机器人逆运动学分析方法

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农业机械学报 2024年第3期55卷 421-430页

作者：柴馨雪李翔毅汤陈昕李秦川徐灵敏浙江理工大学机械工程学院杭州310018 上海交通大学机械系统与振动国家重点实验室上海200240

运动学分析是并联机器人运动学性能评估和结构尺寸优化的基础。现有并联机器人运动学分析方法存在几何建模与几何计算相分离的问题,本文利用共形几何代数(Conformal geometric algebra, CGA)集几何表示和计算为一体的优势,提出一种并联... 详细信息

运动学分析是并联机器人运动学性能评估和结构尺寸优化的基础。现有并联机器人运动学分析方法存在几何建模与几何计算相分离的问题,本文利用共形几何代数(Conformal geometric algebra, CGA)集几何表示和计算为一体的优势,提出一种并联机器人逆运动学分析方法。根据动平台位姿参数给出动平台刚体运动算子,通过共形几何代数框架下的几何积实现动平台上任意点的刚体变换,得到任意点在运动过程中的共形几何表达式;结合机构中尺寸、几何约束,利用内积运算,建立机构运动学方程;根据运动学方程,进行运动学反解计算和速度分析。以3自由度的3-RPS并联机器人和6自由度6-UPS并联机器人为例,对所提方法进行验证,并将逆运动学推导结果与仿真软件所得结果进行了对比,验证了本文提出方法的正确性。该方法将空间向量和旋转表示等几何对象与矩阵乘法、矢量外积等计算方式相结合,使得并联机器人空间几何问题统一在一个代数系统中进行处理,因此分析过程几何直观性较强,简化了运动学逆解分析计算过程。

关键词：并联机器人共形几何代数运动学分析

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葡萄果实内油菜素内酯生物合成调控及生理效应

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分子植物育种 2024年第6期22卷 2060-2068页

作者：李嘉佳李相怡王磊王世平上海交通大学农业与生物学院上海200240

油菜素内酯是调控植物生长发育的重要植物激素,具有促进植物细胞分裂和生长、光合作用和呼吸作用、植株光形态的建成、提高抗逆性以及降低蒸腾等作用,对葡萄果实产量和品质的提高均有着极其重要的贡献。本研究综述了油菜素内酯的生物合... 详细信息

油菜素内酯是调控植物生长发育的重要植物激素,具有促进植物细胞分裂和生长、光合作用和呼吸作用、植株光形态的建成、提高抗逆性以及降低蒸腾等作用,对葡萄果实产量和品质的提高均有着极其重要的贡献。本研究综述了油菜素内酯的生物合成途径及其关键酶、生物合成途径的影响因素,以及其对葡萄果实产量和品质的影响,总结了油菜素内酯对植物光合作用、呼吸作用、蒸腾作用及植物光形态的建成的生理效应。同时,对油菜素内酯与其他植物内源激素的互作网络进行了梳理,并提出未来的研究方向应以油菜素内酯合成相关转录因子、与其他植物激素互作机理和开发新型高效的油菜素内酯类植物调节剂为主。

关键词：葡萄油菜素内酯合成生理效应互作机理

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AI Enabled Wireless Communications with Real Channel Measurements:Channel Feedback

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Journal of Communications and Information Networks 2020年第3期5卷 310-317页

作者： Jiajia Guo xiangyi li Muhan Chen Peiwen Jiang Tingting Yang Weiming Duan Haowen Wang Shi Jin Quan Yu National Mobile Communications Research Laboratory Southeast UniversityNanjing 210096China Peng Cheng Laboratory Shenzhen 518000China Laboratory of Broadband Wireless Technology Shanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai 201800China

Artificial intelligence(AI)has shown great potential in wireless communications.AI-empowered communication algorithms have beaten many traditional algorithms through simulations.However,the existing works just use the simulated datasets to train and test the algorithms,which can not represent the power of AI in practical communication systems.Therefore,Peng Cheng Laboratory holds an AI competition,National Artificial Intelligence Competition(NAIC):AI+wireless communications,in which one of the topics is AI-empowered channel feedback system design using practical measurements.In this paper,we give a baseline neural network design,QuanCsiNet,for this competition,and the details of the channel *** shows excellent performance on channel feedback and the complexity of the neural networks is also given.

关键词： NAIC artificial intelligence CSI feedback channel measurements

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Synergistic effect from coaxially integrated CNTs@MoS_(2)/MoO_(2) composite enables fast and stable lithium storage

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Journal of Energy Chemistry 2021年第4期30卷 449-458页

作者： Hui Lu Kai Tian liangmin Bu Xue Huang xiangyi li Yue Zhao Feng Wang Jianming Bai lijun Gao Jianqing Zhao College of Energy Soochow Institute for Energy and Materials InnovationSSoochow UniversitySuzhou 215006JiangsuChina Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province Soochow UniversitySuzhou 215006JiangsuChina Sustainable Energy Technologies Department Brookhaven National LaboratoryUpton 11973NYUnited States National Synchrotron light Source II Brookhaven National LaboratoryUpton 11973NYUnited States

Molybdenum oxide/sulfide materials are extensively evaluated as high-capacity anode candidates for lithium ion batteries.However,they suffer from rapid capacity decay and poor kinetics.Herein,we report on synergistic effect from structurally integrated coaxial CNTs@MoS_(2)/MoO_(2) composite material on lithium storage,in which MoS_(2)/MoO_(2) nanosheets are conformally decorated on carbon nanotubes(CNTs).In-situ synchrotron X-ray diffraction measurement is performed to elucidate synergistic effect among three MoS_(2),MoO_(2) and CNTs components for lithium storage.Reaction mechanism exploration reveals that the MoO_(2) component undergoes reversible li^(+)intercalation via forming a stable li_(0.98) MoO_(2) phase over a voltage range of 3.0 to 0.01 V vs.li^(+)/li,without experiencing the conversion reaction into metallic Mo,which contributes to long-term stability during charge/discharge cycles.Meanwhile,lithium storage of MoS_(2) is through lithium and sulfur reversible reaction after the initial conversion reaction of lithiated MoS_(2) forming li_(2)S and Mo.The CNTs component enhances electronic conductivity and structural stability by minimizing volume change and reaction strains in the CNTs@MoS_(2)/MoO_(2) composite anode.A desired 68.2%capacity retention upon 2000 cycles at 10 A/g has been demonstrated for the CNTs@MoS_(2)/MoO_(2) anode,revealing prominent reaction kinetics and structural stability for fast and stable lithium storage,superior to various Mo-based anode materials previously reported.The findings from this study,with the unique insight into the role of structural integrity in combining MoS_(2)/MoO_(2) materials with the CNTs substrate,offers a strategy for designing composite anode materials for superior lithium storage performance.

关键词： MoS_(2)/MoO_(2) CNTs Synergistic effect Anode material lithium storage

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健康城市背景下社区公园设计再思考

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城市建筑 2024年第5期21卷 98-103,116页

作者：李相逸田梦袁磊深圳大学建筑与城市规划学院

社区公园作为健康城市重要的组成部分,集运动、休闲、绿化等多种功能于一体,是城市居民活动最便捷的公共空间。文章将分析平时与灾后社区公园扮演的角色及作用,从生理、心理与社会健康三个方面详细探讨社区公园对居民健康的影响机制,并... 详细信息

社区公园作为健康城市重要的组成部分,集运动、休闲、绿化等多种功能于一体,是城市居民活动最便捷的公共空间。文章将分析平时与灾后社区公园扮演的角色及作用,从生理、心理与社会健康三个方面详细探讨社区公园对居民健康的影响机制,并根据既往研究建立社区公园与居民健康关系的理论模型。之后,以在城市居民日常生活范围内提升公共健康水平为导向完善社区公园的设计理念,从宏观、中观、微观三个层面提出相应的设计原则及对应的9项设计策略,以完善社区公园的健康属性,提高其使用价值。社区公园作为健康城市建设中不可缺少的一部分,在疫情之后城市的精细化、网格化发展中将起到更大的作用,本研究将为其设计与优化提供参考和依据。

关键词：社区公园居民健康绿色空间公共卫生规划设计

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Regulation of the water status in three co-occurring phreatophytes at the southern fringe of the Taklamakan Desert

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Journal of Plant Ecology 2008年第4期1卷 227-235页

作者： Frank M.Thomas Andrea Foetzki Dirk Gries Helge Bruelheide xiangyi li Fanjiang Zeng Ximing Zhang Department of Plant Ecology Albrecht von Haller Institute for Plant SciencesGeorg-August-Universitat GottingenUntere Karspule 237073 GottingenGermany Present address:Department of Geobotany University of TrierBehringstraße 2154296 TrierGermany Eidgenossisches Institut fur Agrarokologie und Landwirtschaft Forschungsanstalt AgroscopeReckenholzstrasse 1918046 ZurichSwitzerland Institute of Geobotany and Botanical Garden Martin Luther University Halle-WittenbergAm Kirchtor 106108 Halle(Saale)Germany Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences40 South Beijing Road830011 UrumqiChina

Aims We investigated the regulation of the water status in three predominant perennial C3 phreatophytes(Alhagi sparsifolia,Populus euphratica,Tamarix ramosissima)at typical sites of their occurrence at the southern fringe of the hyperarid Taklamakan Desert(north-west China).Methods In the foreland of the river oasis of Qira(Cele),we determined meteorological variables,plant biomass production,plant water potentials(WL)and the water flux through the plants.We calculated the hydraulic conductance on the flow path from the soil to the leaves(kSL)and tested the effects of kSL,WL and the leaf-to-air difference in the partial pressure of water vapour(Dw)on stomatal regulation using regression analyses.Important Findings Despite high values of plant water potential at the point of turgor loss,all plants sustained WL at levels that were high enough to maintain transpiration throughout the growing season.In A.sparsifolia,stomatal resistance(rs;related to leaf area or leaf mass)was most closely correlated with kSL;whereas in P.euphratica,~70%of the variation in rs was explained by Dw.In T.ramosissima,leaf area-related rs was significantly correlated with WL and kSL.The regulation mechanisms are in accordance with the growth patterns and the occurrence of the species in relation to their distance to the ground water.

关键词： aboveground growth extreme aridity stomatal conductance transpirational demand vapour pressure deficit

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2010–2020年塔里木盆地南部荒漠草地凋落物回收量月动态数据集

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中国科学数据（中英文网络版） 2024年第2期9卷 227-237页

作者：王鹏李向义热甫开提林丽莎曾凡江中国科学院新疆生态与地理研究所新疆荒漠植物根系生态与植被修复重点实验室乌鲁木齐830011 中国科学院新疆生态与地理研究所荒漠与绿洲生态国家重点实验室乌鲁木齐830011 新疆策勒荒漠草地生态系统国家野外科学观测实验站新疆策勒848300 中国科学院大学北京100049

中国科学院新疆策勒荒漠草地生态系统国家野外科学观测研究站(以下简称“策勒站”)地处塔里木盆地南缘,南依昆仑山,北临我国最大的塔克拉玛干沙漠。具有植被群落简单,土壤有机质积累缓慢等特点。凋落物是该区域重要的养分来源。基于对... 详细信息

中国科学院新疆策勒荒漠草地生态系统国家野外科学观测研究站(以下简称“策勒站”)地处塔里木盆地南缘,南依昆仑山,北临我国最大的塔克拉玛干沙漠。具有植被群落简单,土壤有机质积累缓慢等特点。凋落物是该区域重要的养分来源。基于对策勒站荒漠植物群落的长期定位观测,通过对不同植物凋落物器官(枝、叶、果)分组,本文整理统计得到2010–2020年塔里木盆地南部荒漠草地凋落物的回收量月动态数据,同时记载了观测场群落以及土壤养分的年度变化情况。数据的产生严格遵照CERN生物观测规范执行,数据的审核及质量控制由台站与分中心质控人员共同完成。本数据集以期为深入研究塔里木盆地南部荒漠草地凋落物动态变化提供基础数据,为了解和评估极端干旱荒漠生态系统养分循环过程提供理论支撑。

关键词：极端干旱区荒漠草地生态系统凋落物月动态塔里木盆地南部土壤养分循环

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