检索结果-南通市图书馆

Microscopic mechanisms analysis of various dielectric response processes in oil-paper insulation with different insulating states

在线全文

学校读者我要写书评

暂无评论

High Voltage 2024年第3期9卷 591-600页

作者： Zaijun Jiang Jiefeng Liu Xianhao Fan Heng zhang enze zhang Boshu Song Yiyi zhang School of Electrical Engineering Guangxi UniversityNanningGuangxiChina

Various dielectric response processes in the oil-paper insulation are sensitively affected by the insulating states(ageing degrees and moisture contents).However,the existing research is still incomplete in revealing the microscopic mechanisms of various dielectric response processes in oil-paper insulation with different insulating *** this issue,the genetic algorithm is first adopted to extract the Dissado–Hill(D–H)model parameters by simulating the frequency domain spectroscopy(FDS)of oil-paper ***,the change laws of the extracted D–H model parameters are adopted to reveal the microscopic mechanisms of various dielectric response *** mechanisms of four dielectric response processes are studied,which are quasi-dc relax-ation,loss peak relaxation,optical frequency relaxation,and DC ***,due to the dielectric response processes being dominated by various polar particles(methanol,ethanol,furfural,and water molecule),the contents of various ageing by-products dissolved in the insulating oil are measured to support the above *** this respect,a dielectric theoretical reference for the FDS technique to research the insulating states of oil-paper insulation is provided.

关键词： mechanisms insulation relaxation

An improved second-order kinetic model for degradation analysis of transformer paper insulation under non-uniform thermal field

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

High Voltage 2023年第1期8卷 81-90页

作者： Jiefeng Liu Kuo Jiang Qingyin Wang Heng zhang enze zhang Xianhao Fan Yiyi zhang School of Electrical Engineering Guangxi UniversityGuangxiNanningChina

The ageing kinetic model is regarded as an effective tool to describe the degradation of transformer paper ***,the temperature of the transformer winding is unevenly distributed,and the existing ageing kinetic models only depend on experimental data of accelerated thermal ageing at a constant *** this issue,this work proposes an improved second-order kinetic model accounting for the non-uniform thermal ***,oil-paper insulation samples with different ageing stages are prepared under the non-uniform thermal ***,the sample's experimental data of moisture dispersion and distribution of degree of polymerisation are *** this basis,the improved second-order kinetic model is derived to simulate insulating paper's ageing process subjected to an axial temperature ***,the relationship of the parameters in the improved second-order kinetic model with the temperature and moisture content at different winding heights is ***,the proposed model is validated,and the results show that the proposed model is more scientific than the traditional models to describe the degradation of paper *** that respect,this work illustrates an improved second-order kinetic model to provide a reference for the ageing assessment/life prediction of transformer paper insulation under the non-uniform thermal field.

关键词： kinetic thermal insulation

Novel Balun Structure for Dipole Antenna

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Transactions of Nanjing University of Aeronautics and Astronautics 2017年第5期34卷 561-566页

作者： Jin Kui zhang enze Yang Yang He Xiaoxiang Gu Changqing College of Electronic Information Engineering Nanjing University of Aeronautics and Astronautics Ministerial Key Laboratory of JGMT Nanjing University of Science and Technology

A novel balun structure for dipole antenna,which is based on the current distribution on parallel microstrip lines and the emission cancellation characteristic of close equal and opposite currents,is *** principle of the balun structure is first elaborated and ***,a dipole antenna with resonance at 2.45 GHz is constructed using the balun and its radiation pattern is *** simulated and measured reflection coefficients(S_(11))of the antenna are in good agreement 2—3 *** relative bandwidth with an S_(11) of below-10 dB is more than 25%.The antenna also shows a good radiation pattern at 2.45 *** proposed structure can provide a new balun design method for dipole antennas.

关键词： coplanar balun dipole antenna wideband compact balun

A New Method of Assessing Environmental Flows in Channelized Urban Rivers

在线全文

学校读者我要写书评

暂无评论

Engineering 2018年第5期4卷 590-596页

作者： Xin-An Yin Zhifeng Yang enze zhang Zhihao Xu Yanpeng Cai Wei Yang State Key Laboratory of Water Environment Simulation School of Environment Beijing Normal University Beijing 100875 China

Assessing environmental flows （e-flows） for urban rivers is important for water resources planning and river protection, Many e-flow assessment methods have been established based on species＇ habitat pro- vision requirements and pollutant dilution requirements, To avoid flood risk, however, many urban rivers have been transformed into straight, trapezoidal-profiled concrete channels, leading to the disappearance of valuable species, With the construction of water pollution-control projects, pollutant inputs into rivers have been effectively controlled in some urban rivers, For these rivers, the e-flows determined by tradi- tional methods will be very small, and will consequently lead to a low priority being given to river pro- tection in future water resources allocation and management, To more effectively assess the e-flows of channelized urban rivers, we propose three e-flow degrees, according to longitudinal hydrological con- nectivity （high, medium, and low）, in addition to the pollutant dilution water requirement determined by the mass-balance equation, In the high connectivity scenario, the intent is for the e-flows to maintain flow velocity, which can ensure the self-purification of rivers and reduce algal blooms; in the medium connectivity scenario, the intent is for the e-flows to permanently maintain the longitudinal hydrological connectivity of rivers that are isolated into several ponds by means of weirs, in order to ensure the exchange of material, energy, and information in rivers; and in the low connectivity scenario, the intent is for the e-flows to intermittently connect isolated ponds every few days （which is designed to further reduce e-flows）, The proposed methods have been used in Shiwuli River, China, to demonstrate their effectiveness, The new methods can offer more precise and realistic e-flow results and can effectively direct the construction and management of e-flow supply projects,

关键词： Environmental flow Urban river Channelized rivers River restoration

Edge superconductivity in multilayer WTe2 Josephson junction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

National Science Review 2020年第9期7卷 1468-1475页

作者： Ce Huang Awadhesh Narayan enze zhang Xiaoyi Xie Linfeng Ai Shanshan Liu Changjiang Yi Youguo Shi Stefano Sanvito Faxian Xiu State Key Laboratory of Surface Physics and Department of Physics Fudan University Collaborative Innovation Center of Advanced Microstructures SSCU Indian Institute of Science Institute of Physics and Beijing National Laboratory for Condensed Matter Physics Chinese Academy of Sciences School of Physical Sciences University of Chinese Academy of Sciences School of Physics AMBER and CRANN Institute Trinity College Institute for Nanoelectronic Devices and Quantum Computing Fudan University

WTe2, as a type-II Weyl semimetal, has 2D Fermi arcs on the (001) surface in the bulk and 1D helical edge states in its monolayer. These features have recently attracted wide attention in condensed matter ***, in the intermediate regime between the bulk and monolayer, the edge states have not been resolved owing to its closed band gap which makes the bulk states dominant. Here, we report the signatures of the edge superconductivity by superconducting quantum interference measurements in multilayer WTe2Josephson junctions and we directly map the localized supercurrent. In thick WTe2(～ 60 nm), the supercurrent is uniformly distributed by bulk states with symmetric Josephson effect(|Ic~+(B)|=|Ic~-(B)|).In thin WTe2(10 nm), however, the supercurrent becomes confined to the edge and its width reaches up to 1.4 μm and exhibits non-symmetric behavior |Ic~+(B)|≠|Ic~-(B)|. The ability to tune the edge domination by changing thickness and the edge superconductivity establishes WTe2as a promising topological system with exotic quantum phases and a rich physics.

关键词： WTe2 Josephson junction Weyl semimetal edge superconductivity non-symmetric effect

All-electrical switching of a topological non-collinear antiferromagnet at room temperature

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

National Science Review 2023年第2期10卷 123-130页

作者： Yongcheng Deng Xionghua Liu Yiyuan Chen Zongzheng Du Nai Jiang Chao Shen enze zhang Houzhi Zheng Hai-Zhou Lu Kaiyou Wang State Key Laboratory for Superlattices and Microstructures Institute of SemiconductorsChinese Academy of Sciences Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology (SUSTech) International Quantum Academy Beijing Academy of Quantum Information Sciences Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences

Non-collinear antiferromagnetic Weyl semimetals,combining the advantages of a zero stray field and ultrafast spin dynamics,as well as a large anomalous Hall effect and the chiral anomaly of Weyl fermions,have attracted extensive ***,the all-electrical control of such systems at room temperature,a crucial step toward practical application,has not been ***,using a small writing current density of around 5 × 106A·cm-2,we realize the all-electrical current-induced deterministic switching of the non-collinear antiferromagnet Mn3Sn,with a strong readout signal at room temperature in the Si/SiO2/Mn3Sn/AlOxstructure,and without external magnetic field or injected spin *** simulations reveal that the switching originates from the current-induced intrinsic non-collinear spin-orbit torques in Mn3Sn *** findings pave the way for the development of topological antiferromagnetic spintronics.

关键词： spintronics non-collinear antiferromagnetic Weyl semimetals all-electrical switching spin-orbit torques

Switching plasticity in compensated ferrimagnetic multilayers for neuromorphic computing

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2022年第11期31卷 143-148页

作者： Weihao Li Xiukai Lan Xionghua Liu enze zhang Yongcheng Deng Kaiyou Wang State Key Laboratory for Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083 China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049 China Beijing Academy of Quantum Information Sciences Beijing 100083 China Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100049 China

Current-induced multilevel magnetization switching in ferrimagnetic spintronic devices is highly pursued for the application in neuromorphic *** this work,we demonstrate the switching plasticity in Co/Gd ferrimagnetic multilayers where the binary states magnetization switching induced by spin–orbit toque can be tuned into a multistate one as decreasing the domain nucleation ***,the switching plasticity can be tuned by the perpendicular magnetic anisotropy of the multilayers and the in-plane magnetic ***,we used the switching plasticity of Co/Gd multilayers for demonstrating spike timing-dependent plasticity and sigmoid-like activation *** work gives useful guidance to design multilevel spintronic devices which could be applied in high-performance neuromorphic computing.

关键词： switching plasticity compensated ferrimagnet spin-orbit torque spike timing-dependent plasticity sigmoidal neuron handwritten digits recognition neuromorphic computing

Atomic disorders in layer structured topological insulator SnBi2Te4 nanoplates

在线全文

学校读者我要写书评

暂无评论

Nano Research 2018年第2期11卷 696-706页

作者： Yi-Chao Zou Zhi-Gang Chen enze zhang Fantai Kong Yan Lu Lihua Wang John Drennan Zhongchang Wang Faxian Xiu Kyeongjae Cho Jin Zou Materials Engineering University of Queensland Brisbane Australia Centre for Future Materials University of Southern Queensland Springfield Australia Laboratory of Surface Physics and Department of Physics and Collaborative Innovation Center of Advanced Microstructures Fudan University Shanghai China Department of Materials Science & Engineering the University of Texas at Dallas Richardson USA Beijing Key Lab of Microstructure and Property of Advanced Materials Institute of Microstructure and Properties of Advanced Materials Beijing University of Technology Beijing China Centre for Microscopy and Microanalysis University of Queensland Brisbane Australia WPI Advanced Institute for Materials Research Tohoku University Sendai Japan Quantum Materials Science and Technology Department International Iberian Nanotechnology Laboratory Braga Portugal

Identification of atomic disorders and their subsequent control has proven to be a key issue in predicting, understanding, and enhancing the properties of newly emerging topological insulator materials. Here, we demonstrate direct evidence of the cation antisites in single-crystal SnBi2Te4 nanoplates grown by chemical vapor deposition, through a combination of sub-angstr6m-resolution imaging, quantitative image simulations, and density functional theory calculations. The results of these combined techniques revealed a recognizable amount of cation antisites between Bi and Sn, and energetic calculations revealed that such cation antisites have a low formation energy. The impact of the cation antisites was also investigated by electronic structure calculations together with transport measurement. The topological surface properties of the nanoplates were further probed by angle-dependent magnetotransport, and from the results, we observed a two-dimensional weak antilocalization effect associated with surface carriers. Our approach provides a pathway to identify the antisite defects in ternary chalcogenides and the application potential of SnBi2Te4 nanostructures in next-generation electronic and spintronic devices.

关键词： metal chalcogenide antisite defect nanoplate scanning transmissionelectron microscop3~magnetotransport

Suitable Weir Heights to Improve the Provision of Environmental Flows in Urban Rivers

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Engineering 2021年第2期7卷 187-194页

作者： Yuanyuan Sun Xin’an Yin Xianqiang Mao enze zhang Yanwei Zhao State Key Laboratory of Water Environment Simulation School of EnvironmentBeijing Normal UniversityBeijing 100875China

Many studies have been conducted on environmental flow(e-flow)assessment and supply,but e-flow shortages remain common in many urban *** addition to known reasons such as ever-increasing competition among water users and inadequate execution of designed e-flow supply plans,we propose that designing weir heights without explicitly considering e-flows is another major cause of this *** this paper,we suggest that the measures for satisfying e-flows be extended from the water supply stage to the river channel design *** establish a new weir height determination framework that would more effectively satisfy the required *** new framework differs from previous frameworks,in which flood control and water retention are the major concerns and the flow during floods is set as the *** the new framework,e-flow provision and flow velocity maintenance are added concerns and the actual flows for e-flow supply are set as the *** a case study of the new framework’s effectiveness,we applied it to the Shiwuli River,a typical channelized urban river in Hefei,*** old framework specified too-high weir height to meet the e-flow requirements,whereas the new framework offered more reasonable heights that improved e-flow provision.

关键词： Environmental flow Urban rivers River restoration