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Reliability evaluation of modular multilevel converter based on Markov model

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Journal of Modern Power Systems and Clean Energy 2019年第5期7卷 1355-1363页

作者： Liang ZHANG Dan ZHANG Ting HUA Jihong ZHU Gang CHEN tongzhen WEI Ting yang School of Power Electric Engineering Nanjing Institute of TechnologyNanjing 211167China State Key Laboratory of Intelligent Technology and Systems Tsinghua UniversityBeijing 100084China School of Electronic Information and Electrical Engineering Shanghai Jiao Tong UniversityShanghai 200240China State Grid Jiangsu Electric Power Company Xuzhou Power Supply Company Xuzhou 221005China Institute of Electrical Engineering Chinese Academy of SciencesBeijing 100190China

The modular multilevel converter(MMC)is now the most attractive topology for medium and high voltage power conversion applications with several advantages over the traditional voltage source converter(VSC).However,due to a large number of sub-modules(SMs)in the MMC,system reliability is a big challenge in its practical application,where each SM may be considered as a potential point of *** this paper,a reliability evaluation based on the Markov model is proposed for the *** failure rates of the power electronic devices and SMs are firstly ***,the Markov model and the state transition equation of the system are built in detail.A general reliability evaluation function is established,in which the mean time to failure and reliability evaluation of the MMC with redundant SMs are also ***,a practical direct current(DC)distribution example for reliability evaluation is analyzed,and the results verify that the reliability evaluation based on the Markov model could provide a useful reference for project design.

关键词： Modular multilevel converters Reliability evaluation Markov model

Research on a Multiport Parallel Type Hybrid Circuit Breaker for HVDC Grids:Modeling and Design

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CSEE Journal of Power and Energy Systems 2023年第5期9卷 1732-1742页

作者： Xinming Guo Jin Zhu Qingpeng Zeng Hao Xiao tongzhen Wei Institute of Electrical Engineering Chinese Academy of Sciences and University of Chinese Academy of SciencesBeijing 100190China

This paper proposes a star type multiport hybrid circuit breaker(Star-HCB)topology for protection of multiterminal DC *** and stability of high voltage DC(HVDC)grids are determined by their capabilities to withstand DC-side *** order to maintain reliability of HVDC grids,both ends of each line should be equipped with hybrid circuit breakers(HCB).This method will increase expenditure of the HVDC,especially the meshed *** n-port Star-HCB consists of ultra-fast mechanical disconnectors,load current switch and only one transferring branch which is formed by improved half-bridge *** with existing traditional hybrid circuit breakers and other multiport hybrid circuit breakers,the proposed topology can realize the same short-circuit blocking goal using fewer *** mathematical transient process calculation and timedomain simulation of the proposed Star-HCB are given to verify its superiority.

关键词： Fault blocking HVDC grids half-bridge submodule hybrid circuit breaker multi-port

DSFA: cross-scene domain style and feature adaptation for landslide detection from high spatial resolution images

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International Journal of Digital Earth 2023年第1期16卷 2426-2447页

作者： Penglei Li Yi Wang tongzhen Si Kashif Ullah Wei Han Lizhe Wang School of Geophysics and Geomatics China University of GeosciencesWuhanPeople’s Republic of China School of Computer Science Wuhan UniversityWuhanPeople’s Republic of China School of Computer Science China University of GeosciencesWuhanPeople’s Republic of China

Rapid and accurate landslide inventory mapping is significant for emergency rescue and post-disaster ***,deep learning methods exhibit excellent performance in supervised landslide ***,due to differences between cross-scene images,the performance of existing methods is significantly degraded when directly applied to another scene,which limits the application of rapid landslide inventory *** this study,we propose a novel Domain Style and Feature Adaptation(DSFA)method for cross-scene landslide detection from high spatial resolution images,which can leverage labeled source domain images and unlabeled target domain images to mine robust landslide representations for different ***,we mitigate the large discrepancy between domains at the dataset level and feature *** the dataset level,we introduce a domain style adaptation strategy to shift landslide styles,which not only bridges the domain gap,but also increases the diversity of landslide *** the feature level,adversarial learning and domain distance minimization are integrated to narrow large feature distribution discrepancies for learning domain-invariant *** addition,to avoid information omission,we improve the U-Net3+*** experimental results demonstrate that DSFA has superior detection capability and outperforms other methods,showing its great application potential in unsupervised landslide domain detection.

关键词： Landslide detection deep learning remote sensing domain adaptation high spatial resolution

A Novel Discrete Branch Bidirectional Solid-State Circuit Breaker based on Mixture Device

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CES Transactions on Electrical Machines and Systems 2024年第4期8卷 493-503页

作者： Qingpeng Zeng Jin Zhu Songming He Daoqi Wang tongzhen Wei IEEE Institute of Electrical Engineering Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100190China

Solid state circuit breakers(SSCBs)based on fullcontrolled devices such as IGBT and based on half-controlled devices such as thyristor have their respective *** mixture device solid state circuit breaker(M-SSCB)combines the advantages together and can achieve lower loss,high efficiency,active and reliable blocking at the same ***,the conduction loss will increase significantly when the topology expanding to a bidirectional topology because the bidirectional line commutation switch(LCS)structure composed of two groups of IGBTs in reverse *** this paper,a novel discrete branch mixture SSCB(DBM-SSCB)is proposed,bidirectional current only flows through one IGBT that has the obvious conduction losses advantage at the same voltage and current *** one energy-absorbing component is shared by two discrete branches can guarantee optimal costs and *** calculation,the proposed DBM-SSCB can reduce the conduction loss about 30.4%in 10 k V MVDC system,while retaining other advantages of the mixture device SSCB,such as without introducing additional thyristors,charging power supply and the ability to actively interrupt bidirectional fault *** blocking principles and designing guidelines are presented in detail,the feasibility is verified by 500 V-18 A simulation results and scale-down experiment,the engineering calculation and simulation of 10 k V-1 k A prototype is completed and compared with other *** results and comparative analysis show that the proposed DBM-SSCB has both lower losses and significant performance advantages thus has a good engineering application prospect.

关键词： Bidirectional solid-state circuit breakers IGBT Thyristor Conduction losses Engineering prototype System protections

AlPO4包覆改性Li1.167Ni0.167Co0.167Mn0.5O2锂离子电池正极材料及循环性能调控

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硅酸盐学报 2020年第10期48卷 1512-1520页

作者：王同振曹骏杨则恒张卫新合肥工业大学化学与化工学院可控化学与材料化工安徽省重点实验室合肥230009

通过共沉淀法合成Li1.167Ni0.167Co0.167Mn0.5O2正极材料,并以Al(NO3)3·6H2O、K2HPO4、六亚甲基四胺为反应试剂,以柠檬酸–柠檬酸钠作为缓冲溶液,通过调节溶液pH值控制AlPO4的成核与生长速率,从而在富锂材料Li1.167Ni0.167Co0.167Mn0.... 详细信息

通过共沉淀法合成Li1.167Ni0.167Co0.167Mn0.5O2正极材料,并以Al(NO3)3·6H2O、K2HPO4、六亚甲基四胺为反应试剂,以柠檬酸–柠檬酸钠作为缓冲溶液,通过调节溶液pH值控制AlPO4的成核与生长速率,从而在富锂材料Li1.167Ni0.167Co0.167Mn0.5O2颗粒表面均匀包覆AlPO4。研究了不同AlPO4包覆量对Li1.167Ni0.167Co0.167Mn0.5O2正极材料电化学性能的影响。结果表明:1%(质量分数)AlPO4包覆材料表现出高的放电比容量性能(0.1 C首次放电容量可达到265.9 mA·h/g)和优异的循环性能(0.5 C循环150次容量保持率为88%)。材料的优异电化学性能归因于AlPO4包覆改性阻止了电解液与电极材料的直接接触,加速了锂离子扩散并降低电化学阻抗,其Li+扩散系数由3.17×10–15 cm2/s提高到9.03×10–15 cm2/s,电化学阻抗值从152.92Ω降低至62.27Ω。

关键词：锂离子电池共沉淀富锂正极材料包覆磷酸铝

Forecasting and Decision-Making of Systematic Theories for Engineering Geology in Environmental Geoscience

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Journal of Earth Science 1999年第4期18卷 327-328页

作者： Wang Hongxing Yan tongzhen Tang Huiming Teng Weifu(Faculty of Engineering, China University of Geosciences, Wuhan 430074) Faculty of Engineering China University of GeosciencesWuhan 430074

The paper discusses the problems of engineering geology in environmental geoscience from several aspects. For natural sciences and social sciences, it deduces essential theory from logistic cycle model, logic mapping and Verhulst model. It had been discovered that these aspects are equal. However, these were the studies of normal effects. We must establish mathematical model to check from contrary course for gray forecasting and decision-making and answer several questions satisfactorily.

关键词： environmental geoscience gray forecasting and decision-making engineering geology

Health Management of Patients with Type II Diabetes and its Influence on Chronic Complication

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Journal of Clinical and Nursing Research 2020年第3期4卷 107-110页

作者： Jinmin Ren Shoumei Wang tongzhen Zhao Junxia Cui Liqiang Wu Health Management Center Binzhou Municipal Hospital of Traditional Chinese MedicineBinzhou 256600Shandong ProvinceChina Department of neurology Binzhou Second People’s HospitalBinzhou 256800Shandong ProvinceChina Department of Oncology Binzhou Municipal Hospital of Traditional Chinese MedicineBinzhou 256600Shandong ProvinceChina Department of Gastroenterology Binzhou People’s HospitalBinzhou 256600Shandong ProvinceChina Department of Emergency medicine Binzhou Medical University HospitalBinzhou 256603Shandong ProvinceChina

Objectives:To explore the application of health management in patients with type II diabetes and to analyze and compare the incidence of chronic ***:the relevant research work was carried out in our *** September 2018 to September 2019,100 patients with type II diabetes were randomly divided into two groups:one group was given routine nursing intervention,the other group was given health management,and they were named control group and experimental group *** group had 50 patients,the influence of different nursing methods on the incidence of chronic complications in patients was ***:In the one-year followup results,the corresponding complications of patients mainly include cardiovascular disease,kidney disease,cerebrovascular disease,fundus disease and peripheral *** incidence of complications in the experimental group is 10.00%,while that in the control group is 32.00%.in comparison,the incidence in the experimental group is lower,and the data difference between the two group is small(P<0.05),which exists ***:The application of health management method in type II diabetes has significant effect,which can reduce the incidence of chronic complications,improve the quality of life of patients,and has positive significance for clinical development.

关键词： Type II diabetes Health management Chronic complications Impact effect

水以载“思”--庄子之水对先秦思维嬗变之揭櫫

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江淮论坛 2021年第5期 111-116页

作者：廖同真井冈山大学江西吉安343009

水是庄子思想的重要元素。水以载"思",通过水,庄子揭櫫了先秦时期思维方式的嬗变及其情状。庄子之水中,水崇拜展示了先秦时期自然崇拜思维的残留,侧面表明思维从自然宗教信仰向理性转变的趋势;"水喻道"和"水喻命"分别展示了先秦时期理... 详细信息

水是庄子思想的重要元素。水以载"思",通过水,庄子揭櫫了先秦时期思维方式的嬗变及其情状。庄子之水中,水崇拜展示了先秦时期自然崇拜思维的残留,侧面表明思维从自然宗教信仰向理性转变的趋势;"水喻道"和"水喻命"分别展示了先秦时期理性思维中的信仰情愫和前定思维中的生存理性,二者表明了先秦时期思维发展过程中宗教信仰和理性交织的情状。水以载"思"反映了中国古人与自然互利和睦、合而为一的价值取向,展示了思维方式发展的多样性,并从一定程度上揭示了先秦时期隐喻与信仰的内在关系。

关键词：庄子水思维道命

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非小细胞肺癌胸部放疗联合免疫治疗研究进展

中华放射肿瘤学杂志 2022年第6期31卷 579-584页

作者：许桐榛梁军国家癌症中心/国家肿瘤临床医学研究中心/中国医学科学院北京协和医学院肿瘤医院放疗科北京100021 国家癌症中心/国家肿瘤临床医学研究中心/中国医学科学院北京协和医学院肿瘤医院深圳医院放疗科深圳518116

非小细胞肺癌(NSCLC)放疗联合免疫治疗,特别是联合PD-1/PD-L1免疫检查点抑制剂治疗,已成为近年来的研究焦点。探索放疗与免疫治疗的最优空间组合模式,实现各期患者最大限度的获益,是目前临床研究的方向之一。本文对放疗对肿瘤免疫环境... 详细信息

非小细胞肺癌(NSCLC)放疗联合免疫治疗,特别是联合PD-1/PD-L1免疫检查点抑制剂治疗,已成为近年来的研究焦点。探索放疗与免疫治疗的最优空间组合模式,实现各期患者最大限度的获益,是目前临床研究的方向之一。本文对放疗对肿瘤免疫环境的影响、各期NSCLC放疗联合免疫治疗进展以及存在的问题进行综述。

关键词：癌非小细胞肺放射疗法免疫疗法研究进展