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Fast algorithms for singular value decomposition and the inverse of nearly low-rank matrices

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National Science Review 2023年第6期10卷 24-27页

作者： Chen xu Weiwei xu Kaili jing Department of Mathematics and Statistics University of Ottawa School of Mathematics and Statistics Xi'an Jiao Tong University School of Mathematics and Statistics Nanjing University of Information Science and Technology

PROBLEM Matrix computation is a fundamental task in science and engineering;it is recognized as one of the seven computational’giants’of massive data analysis [1],analogous to the seven’dwarfs’in highperformance computing.In recent years,as the scale of datasets rapidly grows,analysts and engineers frequently need to deal with big matrices with a nearly lowrank structure.The big size of a matrix brings great numerical hurdles to matrix computation.In this work,we focus on two typical tasks in matrix computation:singular value decomposition (SVD) and matrix inverse on nearly low-rank matrices that are potentially of big sizes.

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On the scaling law of ramp structures in scalar turbulence

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Atmospheric and Oceanic Science Letters 2018年第4期11卷 372-377页

作者： CHEN Dong-Wei HU Fei xu jing-jing State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of Sciences College of Earth Science University of Chinese Academy of Sciences

斜坡结构在标量湍流中广泛存在,指标量的浓度随时间缓慢爬升然后突然下降的现象,它表明湍流并非完全随机的。基于北京市325米气象铁塔的湍流观测数据,本文利用小波分析提取了温度、水汽和二氧化碳序列中的斜坡结构,其上升部分线性拟合... 详细信息

斜坡结构在标量湍流中广泛存在,指标量的浓度随时间缓慢爬升然后突然下降的现象,它表明湍流并非完全随机的。基于北京市325米气象铁塔的湍流观测数据,本文利用小波分析提取了温度、水汽和二氧化碳序列中的斜坡结构,其上升部分线性拟合的斜率与持续时间存在明显的标度律,三者幂指数相差不大,而且在下降部分也存在类似的规律。同时将斜坡结构上升部分的最大值按时间顺序排列,发现最大值序列依然存在斜坡结构。这表明标量湍流中斜坡结构是自相似的,小尺度的斜坡结构叠加在大尺度的斜坡结构上。

关键词：标量湍流斜坡结构标度律自相似

Multifractal Characteristics of Intermittent Turbulence in the Urban Canopy Layer

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Atmospheric and Oceanic Science Letters 2015年第2期8卷 72-77页

作者： xu jing-jing HU Fei International Center for Climate and Environment Science (ICCES) Institute of Atmospheric Physics Chinese Academy of Science State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC) Institute of Atmospheric Physics Chinese Academy of Sciences

The multifractality of energy and thermal dissipation of fully developed intermittent turbulence is investigated in the urban canopy layer under unstable conditions by the singularity spectrum for the fractal dimensions of sets of singularities characterizing multifractals. In order to obtain high-order moment properties of smallscale turbulent dissipation in the inertial range, an ultrasonic anemometer with a high sampling frequency of 100 Hz was used. The authors found that the turbulent signal could be singular everywhere. Moreover, the singular exponents of energy and thermal dissipation rates are most frequently encountered at around 0.2, which is significantly smaller than the singular exponents for a wind tunnel at a moderate Reynolds number. The evidence indicates a higher intermittency of turbulence in the urban canopy layer at a high Reynolds number, which is demonstrated by the data with high temporal resolution. Furthermore, the temperature field is more intermittent than the velocity field. In addition, a large amount of samples could be used for verification of the results.

关键词：多重分形分形特征间歇性冠层城市奇异指数高时间分辨率湍流耗散

Introducing a drought index to a crop model can help to reduce the gap between the simulated and statistical yield

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Atmospheric and Oceanic Science Letters 2018年第4期11卷 307-313页

作者： WANG Guo-Cheng ZHANG Qing xu jing-jing LAPC Institute of Atmospheric Physics Chinese Academy of Sciences

农田作物生产模型是一个用于评估众多环境和人为因子影响下作物产量变化的重要工具。然而,将所有与作物生长相关的环境因子考虑进模型中是不现实的。因此,模型往往会在一些极端环境条件发生时高估作物的产量。在本文中,我们试图将一个... 详细信息

农田作物生产模型是一个用于评估众多环境和人为因子影响下作物产量变化的重要工具。然而,将所有与作物生长相关的环境因子考虑进模型中是不现实的。因此,模型往往会在一些极端环境条件发生时高估作物的产量。在本文中,我们试图将一个干旱指数(SPEI)应用到一个农田生态系统过程模型(Agro-C)。同时,对比了模型是否考虑干旱指数的情况下与统计产量之间的差距;用于对比的统计产量是黄淮海平原各县近20年来的小麦和玉米统计数据。研究结果显示:在干旱发生的年份里,模型确实部分高估了作物产量;而在模型中加入干旱指数,则能够一定程度提高模型模拟干旱年份粮食作物的精度。

关键词： Agro-C model crop yield drought index

Recent progress in single-molecule fluorescence technology in nanocatalysis

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Nano Research 2022年第12期15卷 10316-10327页

作者： jing Cao Dezheng Zhang Weilin xu State Key Laboratory of Electroanalytical Chemistry and Jilin Province Key Laboratory of Low Carbon Chemical Power Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun130022China University of Science and Technology of China Hefei230026China

Nanoparticles(NPs)play a vital role in the energy catalysis process,so understanding the heterogeneous catalytic properties of nanocatalysts is of great significance for rationally guiding the design of catalysts.However,the traditional method obtains the average information based on the whole and cannot study the catalytic activity of a single nanoparticle.It is critical to investigate the catalytic activity of individual nanoparticles using in situ techniques.This review summarizes some of Prof.xu's recent accomplishments in studying the catalytic behavior of nanoparticles at the single-particle level using single-molecule fluorescence microscopy(SMFM).These achievements include revealing the effect of size,shape,and surface atoms of Pd nanoparticles on catalytic kinetics and dynamics as well as obtaining the activation energy of single Au nanoparticles for catalytic reactions by single-molecule methods.It is the first time to study the kinetics and dynamics of single-atom Pt catalysts.Furthermore,the method was extended to study the Pt deactivation process for hydrogen oxidation reactions as well as the catalytic kinetics of two-electron oxygen reduction reactions of individual Fe3O4 nanoparticles in electrocatalysis.Finally,single-molecule super-resolution techniques were used to observe the evolution of the activity of single Sb doped TiO2 nanorod domains.These studies are of guiding significance for in-depth understanding and realization of rational design of optimal catalysts.

关键词： single-molecule fluorescence microscopy nanocatalysis kinetics and dynamics activation energy electrocatalysis super-resolution imaging

Heading constraint algorithm for foot-mounted PNS using low-cost IMU

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Journal of Systems Engineering and Electronics 2022年第3期33卷 727-736页

作者： GUI jing ZHAO Heming xu Xiang School of Electronic and Information Engineering Soochow UniversitySuzhou 215006China

Foot-mounted pedestrian navigation system(PNS)is a common solution to pedestrian navigation using micro-electro mechanical system(MEMS)inertial sensors.The inherent problems of inertial navigation system(INS)by the traditional algorithm,such as the accumulated errors and the lack of observation of heading and altitude information,have become obstacles to the application and development of the PNS.In this paper,we introduce a heuristic heading constraint method.First of all,according to the movement characteristics of human gait,we use the generalized likelihood ratio test(GLRT)detector and introduce a time threshold to classify the human gait,so that we can effectively identify the stationary state of the foot.In addition,based on zero velocity update(ZUPT)and zero angular rate update(ZARU),the cumulative error of the inertial measurement unit(IMU)is limited and corrected,and then a heuristic heading estimation is used to constrain and correct the heading of the pedestrian.After simulation and experiments with low-cost IMU,the method is proved to reduce the localization error of end-point to less than 1%of the total distance,and it has great value in application.

关键词： pedestrian navigation system(PNS) zero velocity update(ZUPT) gait detection heading constraint

路漫漫其修远兮吾将上下而求索——我的艺术求索之路

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现代艺术 2020年第3期 74-75页

作者：徐菁不详

中华文化辉煌璀璨,博大精深,而中国画作为几千年来当仁不让的国粹,是中华文化的重要载体之一。国画之美,在于它不需要斑斓绚丽的色彩,几抹素雅的淡墨,便可以勾勒出空灵绝美的意境。

关键词：绘画艺术意大利绘画作品风景写生风景油画中央美术学院美术家文艺百家

Development and validation of prognostic nomogram based on log odds of positive lymph nodes for patients with gastric signet ring cell carcinoma

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Chinese Journal of Cancer Research 2020年第6期32卷 778-793页

作者： Zijie xu jing jing Guiliang Ma Department of General Surgery Qingdao Municipal HospitalQingdao UniversityQingdao 266071China Department of Endocrinology Qingdao Municipal HospitalQingdao UniversityQingdao 266071China

Objective: Our aims were to establish novel nomogram models, which directly targeted patients with signet ring cell carcinoma(SRC), for individualized prediction of overall survival(OS) rate and cancer-specific survival(CSS).Methods: We selected 1,365 SRC patients diagnosed from 2010 to 2015 from Surveillance, Epidemiology and End Results(SEER) database, and then randomly partitioned them into a training cohort and a validation cohort.Independent predicted indicators, which were identified by using univariate testing and multivariate analyses, were used to construct our prognostic nomogram models. Three methods, Harrell concordance index(C-index), receiver operating characteristics(ROC) curve and calibration curve, were used to assess the ability of discrimination and predictive accuracy. Integrated discrimination improvement(IDI), net reclassification improvement(NRI) and decision curve analysis(DCA) were used to assess clinical utility of our nomogram models.Results: Six independent predicted indicators, age, race, log odds of positive lymph nodes(LODDS), T stage, M stage and tumor size, were associated with OS rate. Nevertheless, only five independent predicted indicators were associated with CSS except race. The developed nomograms based on those independent predicted factors showed reliable discrimination. C-index of our nomogram for OS and CSS was 0.760 and 0.763, which were higher than American Joint Committee on Cancer(AJCC) 8 th edition tumor-node-metastasis(TNM) staging system(0.734 and 0.741, respectively). C-index of validation cohort for OS was 0.757 and for CSS was 0.773. The calibration curves also performed good consistency. IDI, NRI and DCA showed the nomograms for both OS and CSS had a comparable clinical utility than the TNM staging system.Conclusions: The novel nomogram models based on LODDS provided satisfying predictive ability of SRC both in OS and CSS than AJCC 8 th edition TNM staging system alone.

关键词： Log odds of positive lymph nodes nomograms prognosis signet ring cell

Lactobacillus levels and prognosis of patients with acute myocardial infarction

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Journal of Geriatric Cardiology 2022年第2期19卷 101-114页

作者： jing-jing CAI Yin LIU Jie WANG jing-Xian WANG Yuan WANG Shi-Bo xu Zhuang CUI jing GAO Graduate School Tianjin Medical UniversityTianjinChina Department of Cardiology Xing’anmeng People’s HospitalInner MongoliaChina Clinical School of Thoracic Tianjin Medical UniversityTianjinChina Department of Cardiology Tianjin Chest HospitalTianjinChina School of Public Health Tianjin Medical UniversityTianjinChina Cardiovascular Institute Tianjin Chest HospitalTianjinChina

OBJECTIVE To explore the relationship between Lactobacillus and prognosis of acute myocardial infarction(AMI)patients treated by percutaneous coronary intervention(PCI)and its correlation with clinical parameters.METHODS Consecutive patients with AMI in the coronary care unit of Tianjin Chest Hospital in China who received emergency PCI between July 2017 and December 2018 were enrolled.Subjects’fecal 16 S r DNA gene sequencing data were analyzed and subjects were categorized into low,medium and high level groups according to stool Lactobacillus measurements.The primary endpoints were major adverse cardiac events.Cox regression analysis was used to analyze the relationship between Lactobacillus and prognosis.Spearman correlation analysis and trend tests were used to assess the relationship between Lactobacillus and the clinical indicators.RESULTS The data of 254 patients were included in the analysis.Mean age was 65.90±11.56 years,and 152 patients(59.84%)were male.Follow-up time was 652(548.25-753.00)days.Multivariate Cox regression analysis showed a significantly lower risk of major adverse cardiac events in patients with Lactobacillus>7.1 copies/g[adjusted hazard ratio(HR)=0.216,95%CI:0.094-0.493,P<0.001]compared to patients with Lactobacillus≤3.6 copies/g.Statistically significant differences were shown in ST-segment elevation myocardial infarction(STEMI)(HR=0.217,95%CI:0.085-0.551,P=0.001).Lactobacillus was a protective factor for male smokers aged over 60 years whose brain natriuretic peptide was over 1,000 pg/m L.Spearman correlation analysis showed that Lactobacillus correlated negatively with white blood cells,neutrophils,high-sensitivity C-reactive protein,Troponin T,creatine kinase,creatine kinase-MB and brain natriuretic peptide(downward trend),and correlated positively with left ventricular ejection fraction(upward trend).CONCLUSIONS This study is the first to reveal the correlation between Lactobacillus and inflammation and myocardial damage after STEMI.STEMI patients,especially male smokers aged over

关键词： patients infarction prognosis