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Real-time Abnormal Detection of GWAC Light Curve based on Wavelet Transform Combined with GRU-Attention

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Research in Astronomy and Astrophysics 2024年第5期24卷 151-168页

作者： Hao Li Qing Zhao Long Shao Tao Liu Chenzhou Cui yunfei xu College of Artifcial Intelligence Tianjin University of Science and TechnologyTianjin 300457China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China

Nowadays, astronomy has entered the era of Time-Domain Astronomy, and the study of the time-varying light curves of various types of objects is of great significance in revealing the physical properties and evolutionary history of celestial bodies. The Ground-based Wide Angle Cameras telescope, on which this paper is based, has observed more than 10 million light curves, and the detection of anomalies in the light curves can be used to rapidly detect transient rare phenomena such as microgravity lensing events from the massive data. However, the traditional statistically based anomaly detection methods cannot realize the fast processing of massive data. In this paper, we propose a Discrete Wavelet(DW)-Gate Recurrent Unit-Attention(GRU-Attention) light curve warning model. Wavelet transform has good effect on data noise reduction processing and feature extraction, which can provide richer and more stable input features for a neural network, and the neural network can provide more flexible and powerful output model for wavelet transform. Comparison experiments show an average improvement of 61% compared to the previous pure long-short-term memory unit(LSTM) model, and an average improvement of 53.5% compared to the previous GRU model. The efficiency and accuracy of anomaly detection in previous paper work are not good enough, the method proposed in this paper possesses higher efficiency and accuracy,which incorporates the Attention mechanism to find out the key parts of the light curve that determine the anomalies. These parts are assigned higher weights, and in the actual anomaly detection, the star is detected with83.35% anomalies on average, and the DW-GRU-Attention model is compared with the DW-LSTM model, and the detection result f1 is improved by 5.75% on average, while having less training time, thus providing valuable information and guidance for astronomical observation and research.

关键词： methods data analysis-stars variables general-techniques photometric

Fully Decoupled Branch Energy Balancing Control Method for Modular Multilevel Matrix Converter Based on Sequence Circulating Components

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 235-247页

作者： Zexin Zhao Weijiang Chen Zhichang Yang Guoliang Zhao Bin Han yunfei xu Nianwen Xiang Shulai Wang China Electric Power Research Institute Beijing 100192China State Grid Corporation of China Beijing 100031China State Grid Smart Grid Research Institute Beijing 102209China State Key Laboratory of Advanced Power Transmission Technology Global Energy Interconnection Research InstituteBeijing 102211China Hefei University of Technology Hefei 230009China

The modular multilevel matrix converter(M3C)is a potential frequency converter for low-frequency AC ***,capacitor voltage control of high-voltage and largecapacity M3C is more difficult,especially for voltage balancing between *** solve this problem,this paper defines sequence circulating components and theoretically analyzes the influence mechanism of different sequence circulating components on branch capacitor voltage.A fully decoupled branch energy balancing control method based on four groups of sequence circulating components is *** method can control capacitor voltages of nine branches in horizontal,vertical and diagonal *** influences of both circulating current and voltage,a cross decoupled control is designed to improve control *** results are taken from a low-frequency transmission system based on PSCAD/EMTDC,and effectiveness and precision of the proposed branch energy balancing control method are verified in the case of nonuniform parameters and an unbalanced power system.

关键词： Branch energy balancing control decoupled control low-frequency AC transmission modular multilevel matrix converter(M3C) sequence circulating components

X-Ray Source Classification Using Machine Learning:A Study with EP-WXT Pathfinder LEIA

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Research in Astronomy and Astrophysics 2024年第8期24卷 175-195页

作者： Xiaoxiong Zuo Yihan Tao Yuan Liu yunfei xu Wenda Zhang Haiwu Pan Hui Sun Zhen Zhang Chenzhou Cui Weimin Yuan National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China National Astronomical Data Center Beijing 100101China

X-ray observations play a crucial role in time-domain *** Einstein Probe(EP),a recently launched X-ray astronomical satellite,emerges as a forefront player in the field of time-domain astronomy and high-energy *** a focus on systematic surveys in the soft X-ray band,EP aims to discover high-energy transients and monitor variable sources in the *** achieve these objectives,a quick and reliable classification of observed sources is *** this study,we developed a machine learning classifier for autonomous source classification using data from the EP-WXT Pathfinder—Lobster Eye Imager for Astronomy(LEIA)and EP-WXT *** proposed Random Forest classifier,built on selected features derived from light curves,energy spectra,and location information,achieves an accuracy of approximately 95%on EP simulation data and 98%on LEIA observational *** classifier is integrated into the LEIA data processing pipeline,serving as a tool for manual validation and rapid classification during *** paper presents an efficient method for the classification of X-ray sources based on single observations,along with implications of most effective features for the *** work facilitates rapid source classification for the EP mission and also provides valuable insights into feature selection and classification techniques for enhancing the efficiency and accuracy of X-ray source classification that can be adapted to other X-ray telescope data.

关键词： methods data analysis-X-rays binaries-stars variables general-X-rays bursts

Phase-locked single-mode terahertz quantum cascade lasers array

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Journal of Semiconductors 2024年第6期45卷 87-91页

作者： yunfei xu Weijiang Li Yu Ma Quanyong Lu Jinchuan Zhang Shenqiang Zhai Ning Zhuo Junqi Liu Shuman Liu Fengmin Cheng Lijun Wang Fengqi Liu Key Laboratory of Semiconductor Materials Science Institute of SemiconductorsChinese Academy of SciencesBeijing Key Laboratory of Low Dimensional Semiconductor Materials and DevicesBeijing100083China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Division of Quantum Materials and Devices Beijing Academy of Quantum Information SciencesBeijing 100193China

We demonstrated a scheme of phase-locked terahertz quantum cascade lasers(THz QCLs)array,with a single-mode pulse power of 108 mW at 13 *** device utilizes a Talbot cavity to achieve phase locking among five ridge lasers with first-order buried distributed feedback(DFB)grating,resulting in nearly five times amplification of the single-mode *** to the optimum length of Talbot cavity depends on wavelength,the combination of Talbot cavity with the DFB grating leads to better power amplification than the combination with multimode Fabry-Perot(F-P)*** Talbot cavity facet reflects light back to the ridge array direction and achieves self-imaging in the array,enabling phase-locked operation of *** set the spacing between adjacent elements to be 220μm,much larger than the free-space wavelength,ensuring the operation of the fundamental supermode throughout the laser's dynamic range and obtaining a high-brightness far-field *** scheme provides a new approach for enhancing the single-mode power of THz QCLs.

关键词： quantum cascade lasers phase locking terahertz single mode

剪切流场中油-水界面成膜的影响因素及微观机制

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石油学报 2024年第8期45卷 1244-1256页

作者：李杰训许云飞王志华东北石油大学提高油气采收率教育部重点实验室黑龙江大庆163318 宝石花同方能源科技有限公司北京100086

表面活性剂分子在油-水界面会形成排列有序的结构从而促进界面成膜,厘清这种分子吸附行为对油-水界面成膜的影响及其微观机制,对于构建原油采输工艺油-水乳状液稳定与失稳的方法具有重要意义。以常见阴离子型表面活性剂十二烷基苯磺酸钠... 详细信息

表面活性剂分子在油-水界面会形成排列有序的结构从而促进界面成膜,厘清这种分子吸附行为对油-水界面成膜的影响及其微观机制,对于构建原油采输工艺油-水乳状液稳定与失稳的方法具有重要意义。以常见阴离子型表面活性剂十二烷基苯磺酸钠(SDBS)为例,利用移动平板壁面为原油-SDBS-矿物水界面模拟体系赋予剪切流场,采用非平衡动力学模拟(NEMD)方法,揭示了剪切流场中表面活性剂分子吸附行为对油-水界面成膜的影响,解释了剪切速度、温度、压力及表面活性剂浓度影响界面成膜稳定性的作用机制。研究结果表明,SDBS分子的吸附构型、SDBS分子与水分子形成的氢键,以及油、水相分子的扩散能力均会影响界面成膜稳定性;施加剪切对于油-水界面体系是一个先失稳而又重构稳定的过程,且界面成膜稳定性会随剪切速度的增大而降低;在SDBS浓度同为0.15~0.70 mol/L的区间内,界面膜厚度由静态工况时的1.43~2.13 nm增加至动态剪切工况下的2.74~2.93 nm;温度升高会破坏分子间形成的氢键导致界面失稳,压力升高则缩短了分子间形成氢键的键长,增强了分子间相互作用强度,益于界面保持稳定。

关键词：剪切流场表面活性剂油-水界面膜分子模拟非平衡动力学

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孕前低体重指数对妊娠结局影响的研究

实用预防医学 2024年第3期31卷 350-352页

作者：徐芸菲许晨莹同济大学附属第一妇婴保健院上海200040

目的探讨孕前低体重指数(body mass index,BMI)对妊娠结局的影响,为改善孕前低BMI孕妇的妊娠结局提供依据。方法选取2016年2月—2021年6月在同济大学附属第一妇婴保健院住院分娩的孕妇956例为研究对象,根据孕前体重指数(pre pregnancy b... 详细信息

目的探讨孕前低体重指数(body mass index,BMI)对妊娠结局的影响,为改善孕前低BMI孕妇的妊娠结局提供依据。方法选取2016年2月—2021年6月在同济大学附属第一妇婴保健院住院分娩的孕妇956例为研究对象,根据孕前体重指数(pre pregnancy body mass index,PPBMI)分为低体重组135例、正常体重组576例和超重及肥胖组245例。比较和分析三组不良妊娠结局的发生率及发生风险。结果低体重组妊娠期糖尿病(gestational diabetes mellitus,GDM)、妊娠期高血压(hypertensive disorders of pregnancy,HDP)、大于胎龄儿(large for gestational age,LGA)、小于胎龄儿(small for gestational age,SGA)发生率分别为2.96%、3.70%、1.48%、11.85%,正常体重组GDM、HDP、LGA、SGA发生率分别为8.33%、9.90%、5.73%、4.86%,超重及肥胖组GDM、HDP、LGA、SGA发生率分别为15.92%、17.14%、17.55%、1.63%,低体重组GDM、HDP、LGA发生率明显低于正常体重组和超重及肥胖组(P0.05)。低体重组GDM(OR=0.679,95%CI:0.183~2.520)、HDP(OR=0.373,95%CI:0.118~1.179)、LGA(OR=0.224,95%CI:0.066~0.752)的发生风险明显低于正常体重组(P<0.05或P<0.01),而SGA(OR=4.128,95%CI:1.757~9.702)的发生风险明显高于正常体重组(P<0.01)。结论孕前低BMI不会增加GDM、HDP、PTB、LGA等不良妊娠结局的发生风险,但会显著增加SGA的发生率,因此临床对于孕前低BMI的孕妇应给予合理营养干预以降低SGA的发生风险。

关键词：孕前体重指数低体重超重及肥胖妊娠结局

民族地区巩固拓展脱贫攻坚成果同乡村振兴有效衔接的路径研究

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内蒙古民族大学学报（哲学社会科学版） 2024年第4期50卷 95-105页

作者：许云斐杜玺玺兰州财经大学工商管理学院甘肃兰州730000

随着脱贫攻坚战取得全面胜利,2021年的中央一号文件将“全面推进乡村振兴、加快农业农村现代化”作为主题,这是“三农”工作重心的历史性转移。中国正处于巩固拓展脱贫攻坚成果同乡村振兴有效衔接的关键时期,需要在巩固拓展脱贫攻坚成... 详细信息

随着脱贫攻坚战取得全面胜利,2021年的中央一号文件将“全面推进乡村振兴、加快农业农村现代化”作为主题,这是“三农”工作重心的历史性转移。中国正处于巩固拓展脱贫攻坚成果同乡村振兴有效衔接的关键时期,需要在巩固拓展脱贫攻坚成果的基础上,全面推进乡村振兴。推动民族地区乡村振兴,关涉乡村全面振兴的进度和效益,对进一步铸牢中华民族共同体意识、实现共同富裕具有重要的意义。以海南省白沙黎族自治县为例,分析巩固拓展脱贫攻坚成果同乡村振兴有效衔接的实践路径,全面梳理二者之间的关系,从实施方式、目标对象、侧重方面探寻逻辑框架,总结白沙黎族自治县脱贫攻坚战获得的成果以及脱贫攻坚战取得全面胜利之后面临的挑战,提出相应的改进问题的措施,以期为民族地区巩固拓展脱贫攻坚成果同乡村振兴有效衔接提供借鉴。

关键词：脱贫攻坚乡村振兴衔接路径民族地区

绿色金融改革创新促进企业绿色全要素生产率增长了吗?--来自工业上市公司的绿色转型证据

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金融经济 2024年第2期 46-59页

作者：李孟遥许云飞新疆财经大学

经济绿色转型是实现“双碳”目标的必由之路,企业的绿色转型发展是经济实现绿色转型的关键环节。本文以2012—2019年中国沪深A股工业上市公司为研究对象,使用企业绿色全要素生产率作为企业绿色转型的评价指标,以2017年绿色金融改革创新... 详细信息

经济绿色转型是实现“双碳”目标的必由之路,企业的绿色转型发展是经济实现绿色转型的关键环节。本文以2012—2019年中国沪深A股工业上市公司为研究对象,使用企业绿色全要素生产率作为企业绿色转型的评价指标,以2017年绿色金融改革创新试验区的设立为准自然实验,分析研究绿色金融改革创新对企业绿色转型发展的影响。结果表明,绿色金融改革创新能够显著促进试验区内企业绿色全要素生产率增长率的提升,进而促进企业绿色转型。进一步分析得出,试验区内企业融资约束的缓解和政府政策支持对企业绿色转型有所促进,但其对国有企业和重污染企业的影响却未达预期。本文为绿色金融改革创新的政策效应评估和企业绿色转型发展提供了理论层面的支持和直接经验证据,为各地区制定绿色金融政策提供了参考。

关键词：绿色金融改革创新试验区绿色转型融资约束绿色全要素生产率政策效应评估

基于有源箝位技术的SiC MOSFET串联均压有源驱动电路研究

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中国电机工程学报 2024年第16期44卷 6565-6577,I0023页

作者：项鹏飞郝瑞祥王启丞游小杰徐云飞袁帆北京交通大学电气工程学院北京市海淀区100044 轨道交通安全协同创新中心北京市海淀区100044 先进输电技术国家重点实验室(中国电力科学研究院有限公司) 北京市昌平区102209

功率器件串联技术是实现高压应用的有效途径之一,而串联应用的主要制约因素是串联器件之间的动态均压问题。该文针对不均压条件下串联器件的关断行为进行了理论分析,探究不均压的产生机理,提出一种基于有源箝位技术的碳化硅金属-氧化物... 详细信息

功率器件串联技术是实现高压应用的有效途径之一,而串联应用的主要制约因素是串联器件之间的动态均压问题。该文针对不均压条件下串联器件的关断行为进行了理论分析,探究不均压的产生机理,提出一种基于有源箝位技术的碳化硅金属-氧化物半导体场效应晶体管串联均压有源驱动,其利用有源箝位电路检测串联器件之间的电压不均衡,并箝位电压尖峰,通过反馈控制器件栅极电荷及开关瞬态行为实现均压。该方案不存在不均压的调节周期,即使在交变负载下依然能在每一个开关周期的关断时间内实现均压控制。此外,该文还详细介绍所提出方案的电路原理和参数设计过程,并通过试验验证该方案均压控制效果的有效性。结果表明,所提出方案具有有源箝位电路拓展性强的特点;是独立于原有栅极驱动电路的辅助电路,适用性强;且控制电路结构简单,无需可编程逻辑芯片和额外的信号隔离。

关键词：碳化硅金属-氧化物半导体场效应晶体管串联有源箝位均压控制

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