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Granger causal representation learning for groups of time series

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Science China(Information Sciences) 2024年第5期67卷 56-68页

作者： Ruichu CAI Yunjin WU xiaokai HUANG Wei CHEN Tom Z.J.FU Zhifeng HAO School of Computer Science Guangdong University of Technology Peng Cheng Laboratory College of Science Shantou University

Discovering causality from multivariate time series is an important but challenging *** existing methods focus on estimating the Granger causal structures among multivariate time series,while ignoring the prior knowledge of these time series, e.g., the group of the time series. Focusing on discovering the Granger causal structures among groups of time series, we propose a Granger causal representation learning method to solve this problem. First, we use the multiset canonical correlation analysis method to learn the Granger causal representation of each group of time series. Then, we model the Granger causal relationships among the learned Granger causal representations using a recurrent neural network with temporal information. Finally, we formulate the above two stages into one unified optimization problem, which is efficiently solved using the augmented Lagrangian method. We conduct extensive experiments on synthetic and real-world datasets to validate the correctness and effectiveness of the proposed method.

关键词： Granger causal discovery Granger causal representation learning time series data recurrent neural network multiset canonical correlation analysis

Newtonian limit of Einstein equation with a cosmological constant

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Chinese Physics C 2024年第10期48卷 264-274页

作者： Li-Fang Li Zhoujian Cao xiaokai He Institute of Mechanics Chinese Academy of SciencesBeijing 100190China Institute of Applied Mathematics Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUCASHangzhou 310024China School of Mathematics and Statistics Hunan First Normal UniversityChangsha 410205China

Traditionally,the cosmological constant has been viewed as dark energy that mimics matter with negative *** that matter with negative energy provides a repulsive force,which fundamentally differs from typical gravitational forces,it has been believed that the cosmological constant effectively contributes a repulsive ***,it is important to note that the concept of gravitational force is valid only within the framework of Newtonian *** this study,we demonstrate that the traditional understanding of the gravitational force contributed by the cosmological constant is not entirely *** approach involves investigating the Newtonian limit of the Einstein equation with a cosmological *** subtleties involved in this analysis are discussed in ***,we find that the effect of the cosmological constant on Newtonian gravity is an attractive force rather than a repulsive one for ordinary *** expected,this corrective force is negligibly ***,our findings may offer a way to distinguish between dark energy and the cosmological constant,as one contributes a repulsive force while the other contributes an attractive force.

关键词： cosmological constant dark matter Einstein equation Newtonian limit dark energy

Uncertainty of the Export VAT Rebate Policy:Measurement and Its Effects

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China Finance and Economic Review 2024年第2期13卷 90-111页

作者： Yanzhe Zhang Helian Xu xiaokai Shao School of Economics Hainan University School of Economics and Trade Hunan University International Business School Beijing Foreign Studies University

Based on the export VAT rebate rate data from 2004 to 2015,this paper measures the uncertainty of Chinese export VAT rebate policy by using unexpected fluctuation of export VAT rebate rate,and finds that the index varies across products,years and ***,the paper studies the influence of the uncertainty of export VAT rebate policy on China’s export growth from both theoretical and empirical *** research results show that this uncertainty reduces the expected profit of export enterprises and their optimal output,and significantly reduces the growth rate of the ordinary export that applies the export VAT rebate method,but it has no impact on the processing *** decomposing total value of exports,it is found that the growth in the number of ordinary export relationship and average sales decrease with the increase of uncertainty,while the average price growth rate increases slightly,and these effects are only refl ected in the newly entered export *** findings suggest that when the uncertainty of export VAT rebate policy is high,enterprises are more cautious about entering the ordinary export market and more likely to adopt a lowquantity-high-price strategy.

关键词： export VAT rebate policy uncertainty export growth ordinary export

Effects of sevoflurane on left ventricular function by speckletracking echocardiography in coronary bypass patients: A randomized trial

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The Journal of Biomedical Research 2024年第1期38卷 76-86页

作者： Chanjuan Gong xiaokai Zhou Yin Fang Yanjuan Zhang Linjia Zhu Zhengnian Ding Department of Anesthesiology and Perioperative Medicine the First Affiliated Hospital of Nanjing Medical UniversityNanjingJiangsu 210029China Department of Cardiology the First Affiliated Hospital of Nanjing Medical UniversityNanjingJiangsu 210029China.

The present study aimed to dynamically observe the segmental and global myocardial movements of the left ventricle during coronary artery bypass grafting by transesophageal speckle-tracking echocardiography,and to assess the effect of sevoflurane on cardiac ***-four patients scheduled for the off-pump coronary artery bypass grafting were randomly divided into a sevoflurane-based anesthesia(AS)group and a propofolbased total intravenous anesthesia(AA)*** AS group demonstrated a higher absolute value of left ventricular global longitudinal strain than that of the AA group at both T1(after harvesting all grafts and before coronary anastomosis)and T_(2)(30 min after completing all coronary anastomoses)(P<0.05).Moreover,strain improvement in the segment with the highest preoperative strain was significantly reduced in the AS group,compared with the AA group at both T1 and T_(2)(P<0.01).The flow of the left internal mammary artery-left anterior descending artery graft was superior,and the postoperative concentration of troponin T decreased rapidly in the AS group,compared with the AA group(P<0.05).Compared with total intravenous anesthesia,sevoflurane resulted in a significantly higher global longitudinal strain,stroke volume,and cardiac *** also led to an amelioration in the condition of the arterial ***,sevoflurane significantly reduced strain improvement in the segmental myocardium with a high preoperative strain *** findings need to be replicated in larger studies.

关键词： coronary artery bypass grafting speckle-tracking echocardiography sevoflurane transesophageal echocardiography

Application of machine learning in perovskite materials and devices:A review

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Journal of Energy Chemistry 2024年第7期94卷 254-272页

作者： Ming Chen Zhenhua Yin Zhicheng Shan xiaokai Zheng Lei Liu Zhonghua Dai Jun Zhang Shengzhong(Frank)Liu Zhuo Xu School of Electric Power Civil Engineering and ArchitectureCollege of Physics and Electronics EngineeringState Key Laboratory of Quantum Optics and Quantum Optics DevicesShanxiUniversityTaiyuan030006ShanxiChina Key Laboratory of Applied Surface and Colloid Chemistry National Ministry of EducationShanxi Engineering Lab for Advanced Energy TechnologySchool of Materials Science and EngineeringShaanxi Normal UniversityXi'an 710119ShaanxiChina State Key Laboratory of Catalysis Dalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina

Metal-halide hybrid perovskite materials are excellent candidates for solar cells and photoelectric *** recent years,machine learning(ML)techniques have developed rapidly in many fields and provided ideas for material discovery and *** can be applied to discover new materials quickly and effectively,with significant savings in resources and time compared with traditional experiments and density functional theory(DFT)*** this review,we present the application of ML in per-ovskites and briefly review the recent works in the field of ML-assisted perovskite ***,the advantages of perovskites in solar cells and the merits of ML applied to perovskites are ***,the workflow of ML in perovskite design and some basic ML algorithms are ***,the applications of ML in predicting various properties of perovskite materials and devices are ***,we propose some prospects for the future development of this *** rapid devel-opment of ML technology will largely promote the process of materials science,and ML will become an increasingly popular method for predicting the target properties of materials and devices.

关键词： Machine learning Perovskite Materials design Bandgap engineering Stability Crystal structure

Erratum to:Efficient and stable perovskite solar cells by build-inπ-columns and ionic interfaces in covalent organic frameworks

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Nano Research 2024年第5期17卷 4639-4640页

作者： Riming Nie xiaokai Chen Zhongping Li Weicun Chu Si Ma Changqing Li Xiaoming Liu Yonghua Chen Zhuhua Zhang Wanlin Guo State Key Laboratory of Mechanics and Control of Mechanical Structures Key Laboratoryfor Itligent Nano Materials and Devices of the Ministry of EducationInstitute for Frontier ScienceNanjing University of Aeronautics and AstronauticsNarnjing 210016China Department of Chemical and Biomolecular Engineering Yonsei Universit50 Yonsei roSeodaemun-guSeoul 120749Republic of Korea College of Chemistry jilin UniversityChangchun 130012China Department of Energy and Chemical Engineering Ulsan National Instute of Science and Technology(UNIST)50 UNIST-gilEonyang-eupUju-gunUlsan 44919Republic of Korea Key Laboratory of Flexible Electronics(KLoFE) School of Flexible Electronics(Future Technologies)&Institute of Advanced Materials(IAM)Nanjing Tech University(Nanjing Tech)Nanjing 211816China

Erratum to Nano Research,2023,16(7):9387-9397 htps:/***/0.100/1274-023-5603-040(1)One sentence in the article was unfortunately mispresented on page *** of As shown in Fig.S19 in the ESM,the A2/A2 values of the refere... 详细信息

关键词： COF columns perovskite

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一种环境振动源强预测随机可靠度分析方法

振动与冲击 2024年第6期43卷 336-344页

作者：张校恺韦凯西南交通大学土木工程学院成都610031

不同线路之间工程条件的差异导致18导则半经验模型环境振动源强预测准确度较低,致使后续减振工作浪费大量时间、经济成本。为了提高预测准确度,实现环境振动敏感点的精准筛选,节约减振成本。建立了可以反映隧道壁振动的车辆-轨道-盾构... 详细信息

不同线路之间工程条件的差异导致18导则半经验模型环境振动源强预测准确度较低,致使后续减振工作浪费大量时间、经济成本。为了提高预测准确度,实现环境振动敏感点的精准筛选,节约减振成本。建立了可以反映隧道壁振动的车辆-轨道-盾构隧道耦合振动模型,基于蒙特卡洛(Monte Carlo,MC)法提出了一种环境振动源强预测随机可靠度分析方法,以半经验模型中的3个修正项C_(W)、C_(R)及C_(T)为例,分析了导致修正项预测准确度具有随机不确定性的主要因素并提出了相应的标准化管理建议。主要研究结论如下:所建模型具有较高的计算效率和计算精度,单个工况计算时间为90 s,可弥补MC法耗时的缺点,时域幅值误差在12%以内,源强误差在1 dB以内;同种扣件不同弹性垫板之间非线性载频变刚度的差异是导致C_(W)准确度具有随机不确定性的一个重要原因,该因素会导致源强预测存在-1~+3 dB的误差;不同线路之间钢轨磨耗等级的差异是导致C_(R)准确度具有随机不确定性的一个重要原因,该因素会导致源强预测存在-3~+3 dB的误差;不同中硬土之间弹性模量的差异过大是导致C_(T)准确度具有随机不确定性的一个重要原因,当土体剪切波速在250~375 m/s时C_(T)的准确度较高,当在375~500 m/s时,C_(T)的准确性较低,预测误差可达3 dB;当同时考虑多个修正项带来的误差时,源强预测误差范围可达-4~+9 dB,设计时极有可能采取不符合断面实际要求的减振措施,从而浪费大量减振成本,因此建议严格控制扣件弹性垫板非线性载频变刚度、钢轨磨耗等级等因素的随机性,并以剪切波速375 m/s为界将中硬土划为两类并给出相应的修正项。

关键词：城市轨道交通车辆-轨道耦合动力学环境振动随机振动

寓情于治:社区情感治理的逻辑理路与实践路径

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学习与实践 2024年第6期 51-61页

作者：吴晓凯华东政法大学马克思主义学院上海201620

社区作为情感关系的地域性空间,拥有悠久的情感治理知识谱系和社会文化基础。社区情感治理以柔性的行动方式释放制度权威,使自上而下的标准化、统一化、形式化的行政与法律规范融入到居民的日常话语和生活惯习,从而消弭治理与生活之间... 详细信息

社区作为情感关系的地域性空间,拥有悠久的情感治理知识谱系和社会文化基础。社区情感治理以柔性的行动方式释放制度权威,使自上而下的标准化、统一化、形式化的行政与法律规范融入到居民的日常话语和生活惯习,从而消弭治理与生活之间的鸿沟。在实践层面,情感仪式、情感话语、情感帮扶、情感调解和情感空间等共同形塑了情感治理的总体性框架,以此勾勒出社区情感治理的实践进路。与此同时,社区情感治理在诸多方面有助于实现基层“善治”,对于推进中国式基层治理现代化具有重要的理论和现实意义。

关键词：社区情感治理基层治理实践进路中国式基层治理现代化

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青少年戒烟影响因素及戒烟干预

中华流行病学杂志 2024年第7期45卷 1024-1029页

作者：贾孝凯肖琳中国疾病预防控制中心控烟办公室北京100050

吸烟会严重损害青少年呼吸系统和心血管系统的发育,会加速其成年后慢性病的发生。帮助青少年吸烟者戒烟对于保护青少年健康及降低未来的人群吸烟率均具有重要现实意义。虽然国外对青少年戒烟的影响因素和干预措施已有较多研究探索,但国... 详细信息

吸烟会严重损害青少年呼吸系统和心血管系统的发育,会加速其成年后慢性病的发生。帮助青少年吸烟者戒烟对于保护青少年健康及降低未来的人群吸烟率均具有重要现实意义。虽然国外对青少年戒烟的影响因素和干预措施已有较多研究探索,但国内研究相对较少,尤其是戒烟干预尚处于起步阶段,亟需加强研究与实践。本文从个人、家庭、学校和社会等多个层面综述了国内外影响青少年戒烟的因素,梳理了现有针对青少年的戒烟干预方法,以期为后续相关研究提供参考。

关键词：青少年戒烟影响因素戒烟干预