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High Voltage 2024年第2期9卷 296-308页

作者： lijun yang Zhidong Cheng Li Cheng Ruijin Liao State Key Laboratory of Power Transmission Equipment Technology School of Electrical EngineeringChongqing UniversityChongqingChina

Because DC conductivities of oil-paper materials can be easily affected by electric field and temperature,the electrical properties under electro-thermal coupling of oil-paper materials should be considered when optimising the insulation structure of valve-side winding of the converter transformer.Based on the finite element multi-physical field coupling simulation,the multi-objective optimisation of main insulation structure of valve-side winding is carried out.In view of the high time consuming of multi-physical field calculation and the actual needs of an insulation structure optimisation,the Kriging method and technique for order preference by similarity to the ideal solution(TOPSIS)method are introduced,and combines them with NSGA-II to obtain a joint algorithm that can be used for the optimisation of insulation structure of the converter transformer.By using the joint algorithm of multi-objective optimisation,the insulation structure configuration scheme of valve-side winding is optimised.It can be seen from the experiment result that,on the one hand,the joint algorithm adopted can obtain the insulation structure configuration scheme that meets the design requirements.On the other hand,when facing the configuration scheme optimisation under multi-field coupling,the computational time required by this method is only 0.15%of that required by original genetic algorithm.

关键词： converter insulation coupling

Development of Mixed Insulation Oil as Alternative Liquid Dielectric:A Review

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 1242-1258页

作者： Jian Hao Jingwen Zhang Wenyu Ye Ruijing Liao lijun yang State Key Laboratory of Power Transmission Equipment Technology School of Electrical EngineeringChongqing UniversityChongqing 400044China IEEE CSEE

Use of traditional mineral oil(MO)as a liquid insulation in transformers has spanned more than 130 years.However,MO has poor heat resistance,a low ignition point,and is a non-renewable resource,which does not meet development requirements for high-performance and environmentally friendly insulation oil.Consequently,researchers have explored alternatives such as natural ester(NE)and synthetic ester(SE)oils,as well as mixed insulation oils.Mixed insulating oil is a blend of diverse insulating oil types,with optimal performance achieved by adjusting proportions of base oils.This article summarizes the innovative achievements and development of mixed insulation oil in terms of development of mixed ratio,basic physical chemical properties,electrical properties,thermal stability,and application including operation and maintenance technology.Through these efforts,this article aims to provide recommendations for future development of mixed insulating oils to advance liquid dielectric research based on enhancement mechanisms.

关键词： Environmentally friendly insulation oil ester oils high-performance mineral oil mixed insulation oils

Engineering biomimetic nanosystem targeting multiple tumor radioresistance hallmarks for enhanced radiotherapy

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Science China(Life Sciences) 2024年第7期67卷 1398-1412页

作者： Shuxiang Wang Hongmei Cao Cui-Cui Zhao Qian Wang Dianyu Wang Jinjian Liu lijun yang Jianfeng Liu State Key Laboratory of Advanced Medical Materials and Devices Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear MedicineKey Laboratory of Radiopharmacokinetics for Innovative DrugsTianjin Institutes of Health ScienceInstitute of Radiation MedicineChinese Academy of Medical Sciences&Peking Union Medical CollegeTianjin 300192China Tianjin Medical University Cancer Institute and Hospital National Clinical Research Center for CancerTianjin’s Clinical Research Center for CancerKey Laboratory of Cancer Prevention and Therapy(Tianjin)Key Laboratory of Breast Cancer Prevention and TherapyTianjin Medical UniversityMinistry of EducationTianjin 300060China

Tumor cells establish a robust self-defense system characterized by hypoxia,antioxidant overexpression,DNA damage repair,and so forth to resist radiotherapy.Targeting one of these features is insufficient to overcome radioresistance due to the feedback mechanisms initiated by tumor cells under radiotherapy.Therefore,we herein developed an engineering biomimetic nanosystem(M@HHPt)masked with tumor cell membranes and loaded with a hybridized protein-based nanoparticle carrying oxygens(O_(2))and cisplatin prodrugs(Pt(Ⅳ))to target multiple tumor radioresistance hallmarks for enhanced radiotherapy.After administration,M@HHPt actively targeted and smoothly accumulated in tumor cells by virtue of its innate homing abilities to realize efficient co-delivery of O_(2)and Pt(Ⅳ).O_(2)introduction induced hypoxia alleviation cooperated with Pt(Ⅳ)reduction caused glutathione consumption greatly amplified radiotherapy-ignited cellular oxidative stress.Moreover,the released cisplatin effectively hindered DNA damage repair by crosslinking with radiotherapy-produced DNA fragments.Consequently,M@HHPt-sensitized radiotherapy significantly suppressed the proliferation of lung cancer H1975 cells with an extremely high sensitizer enhancement ratio of 1.91 and the progression of H1975 tumor models with an excellent tumor inhibition rate of 94.7%.Overall,this work provided a feasible strategy for tumor radiosensitization by overcoming multiple radioresistance mechanisms.

关键词： biomimetic nanosystem hypoxia alleviation glutathione consumption oxidative stress amplification DNA damage fixation radiosensitization

Alloyed Pt-Sn nanoparticles on hierarchical nitrogen-doped carbon nanocages for advanced glycerol electrooxidation

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Nano Research 2024年第5期17卷 4055-4061页

作者： Jietao Jiang Liqi Zhou Fengfei Xu Guanghai Chen Xiaoyu Liu Zhen Shen lijun yang Qiang Wu Xizhang Wang Zheng Hu Key Laboratory of Mesoscopic Chemistry of MOE Jiangsu Provincial Laboratory for NanotechnologySchool of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China National Laboratory of Solid State Microstructures Jiangsu Key Laboratory of Artificial Functional MaterialsCollege of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093China

Glycerol is an alternative sustainable fuel for fuel cells,and efficient electrocatalyst is crucial for glycerol oxidation reaction(GOR).The promising Pt catalysts are subject to the inadequate capability of C-C bond cleavage and the susceptibility to poisoning.Herein,Pt-Sn alloyed nanoparticles are immobilized on hierarchical nitrogen-doped carbon nanocages(hNCNCs)by convenient ethylene glycol reduction and subsequent thermal reduction.The optimal Pt_(3)Sn/hNCNC catalyst exhibits excellent GOR performance with a high mass activity(5.9 A·mg_(Pt)^(-1)),which is 2.7 and 5.4 times higher than that of Pt/hNCNC and commercial Pt/C,respectively.Such an enhancement can be mainly ascribed to the increased anti-poisoning and C-C bond cleavage capability due to the Pt_(3)Sn alloying effect and Sn-enriched surface,the high dispersion of Pt_(3)Sn active species due to N-participation,as well as the high accessibility of Pt_(3)Sn active species due to the three-dimensional(3D)hierarchical architecture of hNCNC.This study provides an effective GOR electrocatalyst and convenient approach for catalyst preparation.

关键词： Pt_(3)Sn alloy hierarchical nitrogen-doped carbon nanocages glycerol electrooxidation anti-poisoning C-C bond cleavage

Self-supported NiFe-LDH nanosheets on NiMo-based nanorods as high-performance bifunctional electrocatalysts for overall water splitting at industrial-level current densities

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Nano Research 2024年第5期17卷 3769-3776页

作者： Yan Zhang Biao Feng MingLei Yan Zhen Shen Yiqun Chen Jingyi Tian Fengfei Xu Guanghai Chen Xizhang Wang lijun yang Qiang Wu Zheng Hu Key Laboratory of Mesoscopic Chemistry of Ministry of Education(MOE)and Jiangsu Provincial Lab for Nanotechnology School of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China College of Water Conservancy and Hydropower Engineering Sichuan Agricultural UniversityYa’an 625014China

Efficient,durable and economic electrocatalysts are crucial for commercializing water electrolysis technology.Herein,we report an advanced bifunctional electrocatalyst for alkaline water splitting by growing NiFe-layered double hydroxide(NiFe-LDH)nanosheet arrays on the conductive NiMo-based nanorods deposited on Ni foam to form a three-dimensional(3D)architecture,which exhibits exceptional performances for both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).In overall water splitting,only the low operation voltages of 1.45/1.61 V are required to reach the current density of 10/500 mA·cm^(-2),and the continuous water splitting at an industrial-level current density of 500 mA·cm^(-2) shows a negligible degradation(1.8%)of the cell voltage over 1000 h.The outstanding performance is ascribed to the synergism of the HER-active NiMo-based nanorods and the OER-active NiFe-LDH nanosheet arrays of the hybridized 3D architecture.Specifically,the dense NiFe-LDH nanosheet arrays enhance the local pH on cathode by retarding OH-diffusion and enlarge the electrochemically active surface area on anode,while the conductive NiMo-based nanorods on Ni foam much decrease the charge-transfer resistances of both electrodes.This study provides an efficient strategy to explore advanced bifunctional electrocatalysts for overall water splitting by rationally hybridizing HER-and OER-active components.

关键词： alkaline water splitting bifunctional electrocatalysts layered double hydroxides high durability industrial current densities

Thermo-Flow Performances for the Main-Auxiliary Integrated Natural Draft Dry Cooling System

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Journal of Thermal Science 2024年第3期33卷 1010-1025页

作者： ZHANG Zongyang HOU Yichen ZHOU Hanyu JIA He CHEN Lei KONG Yanqiang WANG Weijia yang lijun DU Xiaoze Key Laboratory of Power Station Energy Transfer Conversion and System of Ministry of Education School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China

Recently,natural draft dry cooling system with the main-auxiliary integrated air-cooled heat exchangers in the up and lower layers,has drawn attention to the electric power industry.This research firstly develops two physical models for the integrated cooling system,namely Case A and Case B.In Case A,the main air-cooled heat exchanger is arranged in the upper layer and the auxiliary air-cooled heat exchanger arranged in the lower layer,while in Case B,the two heat exchanger systems are arranged in the opposite way.And then,directing at the engineering TMCR and TRL 1 working conditions,the unit-local-overall thermo-flow characteristics of Case A and Case B are obtained and compared by numerical simulation.The findings show that,for the auxiliary air-cooled exchanger,Case A has obviously higher cooling performances than Case B,with the difference varying from 5.46%to 7.55%.Whereas,for the main air-cooled exchanger,Case B shows the recovered cooling performances,with the difference changing from 1.15%to 2.99%.Case A is preferably recommended to the engineering application in consideration of more strict cooling demand of the auxiliary cooling system.Conclusively,this research will provide some theoretical guidelines for the design and construction of the main-auxiliary integrated natural draft dry cooling system.

关键词： integrated dry cooling system main air-cooled heat exchanger auxiliary air-cooled heat exchanger upper layer and lower layer thermo-flow performances

Longitudinal Relationship between Gratitude and Benign/Malicious Envy: Evidence from a Cross-Lagged Analysis

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International Journal of Mental Health Promotion 2022年第2期24卷 277-286页

作者： Liying Zhang lijun yang School of Educational Sciences Hunan Normal UniversityChangsha410081China

Though prior research has identiﬁed that gratitude is associated with benign/malicious envy(BeMaS).The pur-pose of this study was to explore the causal relationship between gratitude and BeMaS among Chinese adoles-cents.The two-wave study,in which 906 adolescents participated,includes measurements of gratitude and BeMaS.We employed the structural equation models to test the cross-lagged effect between trait gratitude and BeMaS.The results showed that gratitude could positively predict benign envy and could negatively predict mal-icious envy.Besides,there was no evidence for the reverse or reciprocal relationships between gratitude and BeMaS.Theﬁndings provide further evidence about the causal relationship between gratitude and BeMaS among adolescents.Moreover,these results have implications for gratitude interventions that promote the constructive meaning of envy and reduce the negative inﬂuence of envy.

关键词： Cross-lagged analysis gratitude benign envy malicious envy

Transmit Antenna Selection for Millimeter-Wave MIMO System Based on GBDT

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Journal of Communications and Information Networks 2023年第1期8卷 71-79页

作者： lijun yang Qianyi Zhu Xinchao Ge Lin Guo School of Internet of Things Nanjing University of Posts and TelecommunicationsNanjing 210000China School of Modern Posts Nanjing University of Posts and TelecommunicationsNanjing 210000China.

In millimeter-wave multiple-input multipleoutput(MIMO)systems,transmit antenna selection(TAS)can be employed to reduce hardware complexity and energy consumption when the number of antennas becomes very large.However,the traditional exhaustive search TAS tries all possible antenna combinations which causes high computational complexity.It may limit its application in practice.The main advantage of machine learning(ML)lies in the capability of establishing underlying relations between system parameters and objective,hence being able to shift the computation burden of real-time processing to the offline training phase.Based on this advantage,introducing ML to TAS is a promising way to tackle the high computational complexity problem.Although the existing ML-based algorithms try to approach the optimal performance,there is still a large room for improvement.In this paper,considering the secure transmission of the system,we model the TAS problem as a multi-class classification problem and propose an efficient antenna selection algorithm based on gradient boosting decision tree(GBDT),in which we consider the system security capacity and computational complexity as the optimization objectives.On the one hand,the system security performance is improved because its achievable security capacity is close to the traditional exhaustive search algorithm.On the other hand,compared with the exhaustive search algorithm and existing ML-based algorithms,the training efficiency is significantly improved with the complexity O(N),where N is the number of transmitting antenna.In addition,the performance of the proposed algorithm is evaluated in mmWave MIMO system by employing New York University simulator(NYUSIM)model,which is based on the real channel measurement.Performance analysis show that the proposed GBDT-based scheme can effectively improve the system secrecy capacity and significantly reduce the computational complexity.

关键词： millimeter-wave massive MIMO GBDT antenna selection ML

Influence of contact layer on the sulphur corrosion of copper conductors in power transformers

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High Voltage 2022年第1期7卷 176-184页

作者： lijun yang Dong Ding Yuan Yuan Sihang Gao Yuncai Lu State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing UniversityChongqingChina College of Material Science and Engineering Chongqing UniversityChongqingChina Key Laboratory of Industrial Internet of Things and Networked Control Ministry of EducationChongqing University of Posts and TelecommunicationsChongqingChina State Grid Jiangsu Electric Power Co. Ltd.Electric Power Research InstituteNanjingChina

Owing to the corrosive sulphides in the mineral insulating oil such as dibenzyl disul-phide(DBDS),copper windings in oil‐immersed transformers may suffer sulphur corrosion.This study investigates the influence of different contact conditions on the corrosion of copper conductors in transformers.Oil‐immersed accelerated corrosion experiment was conducted on copper conductors with various contact materials and different layers of insulating paper.The surface micromorphology,deposition compo-nent and the potentiodynamic polarization characteristics of copper conductors were explored.The results show that copper with different contact materials suffer sulphur corrosion;conversely,bare copper rarely does.It was also verified that the existence of a particular gap between copper and contact layer is a significant factor in sulphur corrosion by the formation of a concentration cell on the copper surface.The insu-lating paper wrapped around copper conductors does not increase the corrosion ten-dency of copper;however,it contributes to the formation of a region concentrated with DBDS,Cu^(2+),H^(+)by adsorption and impediment,which plays a key role in facilitating the sulphur corrosion of copper conductors.Moreover,sulphur corrosion can also occur on other metal parts in transformers when there is a particular gap on surfaces other than copper.

关键词： corrosion copper sulphur

Cold sintering process for fabrication of a superhydrophobic ZnO-polytetrafluoroethylene(PTFE)ceramic composite

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Journal of Advanced Ceramics 2023年第9期12卷 1758-1766页

作者： Xuetong Zhao yang yang Li Cheng Jing Guo Shenglin Kang Yuchen Li Xilin Wang lijun yang Ruijin Liao State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqing 400044China State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China Engineering Laboratory of Power Equipment Reliability in Complicated Coastal Environments Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China

Composite coatings or films with polytetrafluoroethylene(PTFE)are typically utilized to offer superhydrophobic surfaces.However,the superhydrophobic surfaces usually have limited durability and require complicated fabrication methods.Herein,we report the successful integration of PTFE with ZnO ceramics to achieve superhydrophobicity via a one-step sintering method,cold sintering process(CSP),at 300℃.(1–x)ZnO–x PTFE ceramic composites with x ranging from 0 to 70 vol%are densified with relative density of over 97%.Micro/nano-scale PTFE polymer is dispersed among ZnO grains forming polymer grain boundary phases,which modulate surface morphology and surface energy of the ZnO–PTFE ceramic composites.For the 60 vol%ZnO–40 vol%PTFE ceramic composite,superhydrophobic properties are optimized with static water contact angles(WCAs)and sliding angles(SAs)of 162°and 7°,respectively.After abrading into various thicknesses(2.52,2.26,and 1.99 mm)and contaminating with graphite powders on the surface,WCA and SA are still maintained with a high level of 157°–160°and 7°–9.3°,respectively.This work indicates that CSP provides a promising pathway to integrate polymers with ceramics to realize stable superhydrophobicity.

关键词： cold sintering process(CSP) ZnO-polytetrafluoroethylene(PTFE)ceramic composites contact angles sliding angles(SAs) superhydrophobicity