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The importance of data assimilation components for initial conditions and subsequent error growth

Science China Earth Sciences 2024年第1期67卷 105-116页

作者： Zhongrui WANG Haohao SUN Lili LEI zhe-min tan Yi ZHANG Key Laboratory of Mesoscale Severe Weather Ministry of Educationand School of Atmospheric SciencesNanjing UniversityNanjing 210023China Frontiers Science Center for Critical Earth Material Cycling Nanjing UniversityNanjing 210023China

Despite a specific data assimilation method,data assimilation(DA)in general can be decomposed into components of the prior information,observation forward operator that is given by the observation type,observation error covariances,and background error covariances.In a classic Lorenz model,the influences of the DA components on the initial conditions(ICs)and subsequent forecasts are systematically investigated,which could provide a theoretical basis for the design of DA for different scales of interests.The forecast errors undergo three typical stages:a slow growth stage from 0 h to 5 d,a fast growth stage from 5 d to around 15 d with significantly different error growth rates for ensemble and deterministic forecasts,and a saturation stage after 15 d.Assimilation strategies that provide more accurate ICs can improve the predictability.Cycling assimilation is superior to offline assimilation,and a flow-dependent background error covariance matrix(Pf)provides better analyses than a static background error covariance matrix(B)for instantaneous observations and frequent time-averaged observations;but the opposite is true for infrequent time-averaged observations,since cycling simulation cannot construct informative priors when the model lacks predictive skills and the flow-dependent Pf cannot effectively extract information from low-informative observations as the static B.Instantaneous observations contain more information than time-averaged observations,thus the former is preferred,especially for infrequent observing systems.Moreover,ensemble forecasts have advantages over deterministic forecasts,and the advantages are enlarged with less informative observations and lower predictive-skill model priors.

关键词： Data assimilation Atmospheric predictability Background error covariances Ensemble forecasts

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Hemoglobin loss method calculates blood loss during pancreaticoduodenectomy and predicts bleeding-related risk factors

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World Journal of Gastrointestinal Surgery 2024年第2期16卷 419-428页

作者： Chao Yu Yi-min Lin Guo-zhe Xian Department of Hepatobiliary Surgery Shandong Provincial Hospital Affiliated to Shandong First Medical UniversityJinan 250021Shandong ProvinceChina

BACKGROUND The common clinical method to evaluate blood loss during pancreaticoduoden-ectomy(PD)is visual inspection,but most scholars believe that this method is extremely subjective and inaccurate.Currently,there is no accurate,objective me-thod to evaluate the amount of blood loss in PD patients.We retrospectively analyzed the clinical data of 341 patients who underwent PD in Shandong Provincial Hospital from March 2017 to February 2019.According to different surgical methods,they were divided into an open PD(OPD)group and a laparoscopic PD(LPD)group.The differences and correlations between the in-traoperative estimation of blood loss(IEBL)obtained by visual inspection and the intraoperative calculation of blood loss(ICBL)obtained using the Hb loss method were analyzed.ICBL,IEBL and perioperative calculation of blood loss(PCBL)were compared between the two groups,and single-factor regression analysis was performed.RESULTS There was no statistically significant difference in the preoperative general patient information between the two groups(P>0.05).PD had an ICBL of 743.2(393.0,1173.1)mL and an IEBL of 100.0(50.0,300.0)mL(P200μmol/L(95%CI:7.09-644.26;P=0.045)were independent risk factors for PCBL.The ICBLs of the LPD group and OPD group were 767.7(435.4,1249.0)mL and 663.8(347.7,1138.2)mL,respectively(P>0.05).The IEBL of the LPD group 200.0(50.0,200.0)mL was slightly greater than that of the OPD group 100.0(50.0,300.0)mL(P>0.05).PCBL was greater in the LPD group than the OPD group[1061.6(612.3,1632.3)mL vs 806.1(375.9,1347.6)mL](P<0.05).CONCLUSION The ICBL in patients who underwent PD was greater than the IEBL,but there is a certain correlation bet

关键词： Pancreaticoduodenectomy Hemoglobin loss Calculated blood loss Estimated blood loss

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On the relationship between tropical cyclone size and environmental helicity in the South China Sea

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Atmospheric and Oceanic Science Letters 2022年第4期15卷 32-37页

作者： min Li Kekuan Chu Jian-Feng Gu zhe-min tan School of Atmospheric Sciences Nanjing UniversityNanjingChina Key Laboratory of Mesoscale Severe Weather/ministry of Education Nanjing UniversityNanjingChina Department of Meteorology University of ReadingLondonUK

本文利用2001–2019年间的ERA5再分析数据集和热带气旋(TC)最佳路径观测,分析了中国南海TC的外围尺度与环境变量之间的关系.研究发现,低层环境螺旋度与TC外围尺度具有显著的正相关.大的环境螺旋度有利于TC外围对流的增强和组织化,与之... 详细信息

本文利用2001–2019年间的ERA5再分析数据集和热带气旋(TC)最佳路径观测,分析了中国南海TC的外围尺度与环境变量之间的关系.研究发现,低层环境螺旋度与TC外围尺度具有显著的正相关.大的环境螺旋度有利于TC外围对流的增强和组织化,与之对应的径向入流和角动量输送有利于TC外围尺度的维持或扩张.此外,螺旋度的非对称分布与TC外围尺度的非对称性结构也密切相关.环境螺旋度作为一个包含TC外围对流强度和组织化程度等信息的综合动力因子,为理解TC外围尺度变化提供了不同的视角.

关键词：热带气旋热带气旋外围尺度螺旋度绝对角动量

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Typhoon Track,Intensity,and Structure:From Theory to Prediction

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Advances in Atmospheric Sciences 2022年第11期39卷 1789-1799页

作者： zhe-min tan Lili LEI Yuqing WANG Yinglong XU Yi ZHANG Key Laboratory of Mesoscale Severe Weather Ministry of Educationand School of Atmospheric SciencesNanjing UniversityNanjing 210063China International Pacific Research Center and Department of Atmospheric SciencesSchool of Ocean and Earth Science and TechnologyUniversity of Hawaii at ManoaHonoluluHawaii 96822USA National Meteorological Center of CMA Beijing 100081China

To improve understanding of essential aspects that influence forecasting of tropical cyclones(TCs),the National Key Research and Development Program,ministry of Science and Technology of the People's Republic of China conducted a five-year project titled“Key Dynamic and Thermodynamic Processes and Prediction for the Evolution of Typhoon Intensity and Structure”(KPPT).Through this project,new understandings of TC intensification,including outer rainbanddriven secondary eyewall formation and the roles of boundary layer dynamics and vertical wind shear,and improvements to TC data assimilation with integrated algorithms and adaptive localizations are achieved.To promote a breakthrough in TC intensity and structure forecasting,a new paradigm for TC evolution dynamics(i.e.,the correlations,interactions,and error propagation among the triangle of TC track,intensity,and structure)is proposed;and an era of dynamic-constrained,big-data driven,and strongly coupled data assimilation at the subkilometer scale and seamless prediction is expected.

关键词： typhoons track intensity structure theories predictions

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Experimental and numerical study on protective effect of RC blast wall against air shock wave

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Defence Technology（防务技术） 2024年第1期31卷 567-579页

作者： Xin-zhe Nian Quan-min Xie Xin-li Kong Ying-kang Yao Kui Huang State Key Laboratory of Precision Blasting Jianghan UniversityWuhan430056China Hubei Key Laboratory of Blasting Engineering Jianghan UniversityWuhan430056China Hubei(Wuhan)Institute of Explosion and Blasting Technology Jianghan UniversityWuhan430056China College of Defense Engineering Army Engineering University of PLANanjing210007China Institute of Defense Engineering AMSPLALuoyang471023China

Prototype experiments were carried out on the explosion-proof performance of the RC blast wall.The mass of TNT detonated in the experiments is 5 kg and 20 kg respectively.The shock wave overpressure was tested in different regions.The above experiments were numerically simulated,and the simulated shock wave overpressure waveforms were compared with that tested and given by CONWEP program.The results show that the numerically simulated waveform is slightly different from the test waveform,but similar to CONWEP waveform.Through dimensional analysis and numerical simulation under different working conditions,the equation for the attenuation rate of the diffraction overpressure behind the blast wall was obtained.According to the corresponding standards,the degree of casualties and the damage degree of the brick concrete building at a certain distance behind the wall can be determined when parameters are set.The above results can provide a reference for the design and construction of the reinforced concrete blast wall.

关键词： Blast wall Shock wave Diffraction Overpressure Protection

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Evaluation of a Regional Ensemble Data Assimilation System for Typhoon Prediction

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Advances in Atmospheric Sciences 2022年第11期39卷 1816-1832页

作者： Lili LEI Yangjinxi GE zhe-min tan Yi ZHANG Kekuan CHU Xin QIU Qifeng QIAN Key Laboratory of Mesoscale Severe Weather/ministry of Education School of Atmospheric SciencesNanjing UniversityNanjing 210063China National Meteorological Center China Meteorological AdministrationBeijing 100081China

An ensemble Kalman filter(EnKF) combined with the Advanced Research Weather Research and Forecasting model(WRF) is cycled and evaluated for western North Pacific(WNP) typhoons of year 2016. Conventional in situ data, radiance observations, and tropical cyclone(TC) minimum sea level pressure(SLP) are assimilated every 6 h using an 80-member ensemble. For all TC categories, the 6-h ensemble priors from the WRF/EnKF system have an appropriate amount of variance for TC tracks but have insufficient variance for TC intensity. The 6-h ensemble priors from the WRF/EnKF system tend to overestimate the intensity for weak storms but underestimate the intensity for strong storms. The 5-d deterministic forecasts launched from the ensemble mean analyses of WRF/EnKF are compared to the NCEP and ECMWF operational control forecasts. Results show that the WRF/EnKF forecasts generally have larger track errors than the NCEP and ECMWF forecasts for all TC categories because the regional simulation cannot represent the large-scale environment better than the global simulation. The WRF/EnKF forecasts produce smaller intensity errors and biases than the NCEP and ECMWF forecasts for typhoons, but the opposite is true for tropical storms and severe tropical storms. The 5-d ensemble forecasts from the WRF/EnKF system for seven typhoon cases show appropriate variance for TC track and intensity with short forecast lead times but have insufficient spread with long forecast lead times. The WRF/EnKF system provides better ensemble forecasts and higher predictability for TC intensity than the NCEP and ECMWF ensemble forecasts.

关键词： ensemble Kalman filter typhoon prediction ensemble forecast

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Tracing monoclinic distortion in NCM532 cathode materials by in situ high-energy synchrotron X-ray diffraction

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Progress in Natural Science:Materials International 2024年第2期34卷 274-279页

作者： min Dong Qingya Sun Zhihua Wang Zixin Rui zhe Zhang He Zhu Si Lan Herbert Gleiter Institute of Nanoscience School of Materials Science and Engineering Nanjing University of Science and Technology School of Mechanical Engineering Nanjing University of Science and Technology School of Materials Science and Engineering Henan University of Technology Center for Neutron Scattering City University of Hong Kong Shenzhen Research Institute

Layered LiNixCoyMnzO2（NCM） cathode materials have emerged as the best choice for high-energy-density lithium-ion batteries for powering electric vehicles.Despite significant research efforts,the understanding of complex structural dynamics during lithium（de-） intercalation still remains a subject of debate,especially in scenarios where morphology and composition vary.In this study,we carried out in situ high-energy synchrotron X-ray diffraction experiments on commercial NCM523cathode materials in both single crystal and polycrystalline forms to probe the structural changes during charging and discharging in detail.Our findings reveal that both single crystal and polycrystalline materials exhibit typical H1-H2-H3 phase transitions.However,in polycrystalline NCM532,a monoclinic intermediate phase emerges between the H1 and H2 phases.During this process,symmetry reduces from R-3m to C2/m,which is attributed to a shear distortion along the ab plane.In contrast,for single crystal materials,the H1 phase directly transforms into the H2 phase without the monoclinic phase.The observed monoclinic distortion significantly impacts structural stability and material cycling performance.This study provides new insight into the structural dynamics in NCM532 cathode materials,particularly concerning morphology-dependent behaviors,which could deepen our understanding of the relationship between NCM material structures and their performance.

关键词： CHEMISTRY

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Collembolans maintain a core microbiome responding to diverse soil ecosystems

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Soil Ecology Letters 2024年第1期6卷 33-46页

作者： zhe-Lun Liu Dong Zhu Yi-Fei Wang Yong-Guan Zhu min Qiao State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China Key Lab of Urban Environment and Health Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China

The unique gut habitat led to a core intestinal micro-biome in diverse soil ecosystems.The collembolan guts may help eliminate soil pathogens.Host-selection carried more weight on community assembly of gut microbiome.Soil invertebrates are widely distributed in the ecosystem and are essential for soil ecological processes.Inverte-brate gut microbiome plays an important role in host health and has been considered as a hidden microbial repository.However,little is known about how gut microbiome in soil invertebrates respond to diverse soil ecosystems.Based on a laboratory microcosm experiment,we characterized the assembling of microbiome of soil collembolans(Folsomia candida)from six representative regions of the soil ecosystem which they inhabit.Results showed that collembolan gut microbial communities differed significantly from their surrounding soil microbial communities.A dominant core gut microbiome was identified in gut habitat.Community analyses indicated that deterministic process dominated in the community assembly of collembolan gut microbiome.The results further demonstrate a dominant contribution of host selection in shaping gut microbiome.It is also worthy to mention that pathogens,such as common agricultural phytopathogenic fungi Fusarium,were involved in core microbiome,indicating that collembolans could act as vectors of pathogens.Our results unravelled the existence of gut core microbiome of collembolans in soil ecosystems and provided new insights for under-standing the crucial role of gut microbiome of soil fauna in maintaining microbial biodiversity and stability of soil ecosystems.

关键词： gut microbiome collembolan core microbiome community assembly

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Beam based alignment using a neural network

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Nuclear Science and Techniques 2024年第4期35卷 108-118页

作者： Guan-Liang Wang Ke-min Chen Si-Wei Wang zhe Wang Tao He Masahito Hosaka Guang-Yao Feng Wei Xu National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei 230029China Diamond Light Source Oxfordshire OX110DEUK

Beams typically do not travel through the magnet centers because of errors in storage rings.The beam deviating from the quadrupole centers is affected by additional dipole fields due to magnetic field feed-down.Beam-based alignment(BBA)is often performed to determine a golden orbit where the beam circulates around the quadrupole center axes.For storage rings with many quadrupoles,the conventional BBA procedure is time-consuming,particularly in the commissioning phase,because of the necessary iterative process.In addition,the conventional BBA method can be affected by strong coupling and the nonlinearity of the storage ring optics.In this study,a novel method based on a neural network was proposed to determine the golden orbit in a much shorter time with reasonable accuracy.This golden orbit can be used directly for operation or adopted as a starting point for conventional BBA.The method was demonstrated in the HLS-II storage ring for the first time through simulations and online experiments.The results of the experiments showed that the golden orbit obtained using this new method was consistent with that obtained using the conventional BBA.The development of this new method and the corresponding experiments are reported in this paper.

关键词： Golden orbit Beam-based alignment Neural network Storage ring

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Observation of transition from superfluorescence to polariton condensation in CsPbBr3 quantum dots film

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Light(Science & Applications) 2024年第2期13卷 316-324页

作者： Danqun Mao Linqi Chen zheng Sun min Zhang zhe-Yu Shi Yongsheng Hu Long Zhang Jian Wu Hongxing Dong Wei Xie Hongxing Xu State Key Laboratory of Precision Spectroscopy East China Normal UniversityShanghai 200241China Key Laboratory of Materials for High-Power Laser Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences201800 ShanghaiChina Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuanShanxi 030006China Chongqing Key Laboratory of Precision Optics Chongqing Institute of East China Normal UniversityChongqing 401121China CAS Center for Excellence in Ultraintense Laser Science Shanghai 201800China School of Physics and Technology Center for Nanoscience and NanotechnologyWuhan UniversityWuhan 430072China

The superfluorescence effect has received extensive attention due to the many-body physics of quantum correlation in dipole gas and the optical applications of ultrafast bright radiation field based on the cooperative quantum state.Here,we demonstrate not only to observe the superfluorescence effect but also to control the cooperative state of the excitons ensemble by externally applying a regulatory dimension of coupling light fields.A new quasi-particle called cooperative exciton-polariton is revealed in a light-matter hybrid structure of a perovskite quantum dot thin film spin-coated on a Distributed Bragg Reflector.Above the nonlinear threshold,polaritonic condensation occurs at a nonzero momentum state on the lower polariton branch owning to the vital role of the synchronized excitons.The phase transition from superfluorescence to polariton condensation exhibits typical signatures of a decrease of the linewidth,an increase of the macroscopic coherence as well as an accelerated radiation decay rate.These findings are promising for opening new potential applications for super-brightness and unconventional coherent light sources and could enable the exploitation of cooperative effects for quantum optics.

关键词： quantum condensation polar

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