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供电电压闪变对异步电动机转子故障在线检测的影响及应对

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中国电机工程学报 2024年第11期44卷 4525-4534,I0030页

作者：许伯强孙丽玲华北电力大学电力工程系河北省保定市071003

供电电压闪变可能对异步电动机转子故障在线检测产生不利影响,导致基于定子电流信号分析(motor current signature analysis,MCSA)的转子故障在线检测方法失效。通过理论分析,揭示供电电压闪变恶化转子故障在线检测性能的机制。提出免... 详细信息

供电电压闪变可能对异步电动机转子故障在线检测产生不利影响,导致基于定子电流信号分析(motor current signature analysis,MCSA)的转子故障在线检测方法失效。通过理论分析,揭示供电电压闪变恶化转子故障在线检测性能的机制。提出免于供电电压闪变影响的异步电动机转子故障在线检测方法,首先,根据转子故障主特征频率分量预判转子健康或故障;继而,根据转子故障独有的辅助特征频率分量进一步确认转子健康或故障。仿真与实验结果证明了该方法的有效性。

关键词：异步电动机转子故障转子断条供电电压闪变在线检测

Unveiling a novel metal-to-metal transition in LuH_(2):Critically challenging superconductivity claims in lutetium hydrides

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Matter and Radiation at Extremes 2024年第3期9卷 65-73页

作者： Dong Wang Ningning Wang Caoshun Zhang Chunsheng Xia Weicheng Guo Xia Yin Kejun Bu Takeshi Nakagawa Jianbo Zhang Federico Gorelli Philip Dalladay-Simpson Thomas Meier Xujie Lü liling sun Jinguang Cheng Qiaoshi Zeng Yang Ding Ho-kwang Mao Center for High-Pressure Science and Technology Advanced Research Beijing 100094China Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of SciencesBeijing 100190China Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments(MFree) Shanghai Advanced Research in Physical Sciences(SHARPS)Shanghai 201203China

Following the recent report by Dasenbrock-Gammon et al.[Nature 615,244–250(2023)]of near-ambient superconductivity in nitrogendoped lutetium trihydride(LuH_(3-δ)N_(ε)),significant debate has emerged surrounding the composition and interpretation of the observed sharp resistance ***,we meticulously revisit these claims through comprehensive characterization and *** definitively identify the reported material as lutetium dihydride(LuH_(2)),resolving the ambiguity surrounding its *** similar conditions(270–295 K and 1–2 GPa),we replicate the reported sharp decrease in electrical resistance with a 30%success rate,aligning with the observations by Dasenbrock-Gammon et ***,our extensive investigations reveal this phenomenon to be a novel pressure-induced metal-to-metal transition intrinsic to LuH_(2),distinct from ***,nitrogen doping exerts minimal impact on this *** work not only elucidates the fundamental properties of LuH_(2)andLuH_(3),but also critically challenges the notion of superconductivity in these lutetium hydride *** findings pave the way for future research on lutetium hydride systems,while emphasizing the crucial importance of rigorous verification in claims of ambient-temperature superconductivity.

关键词： resistance hydride superconductivity

基于循证的高校图书馆主题书展服务效果测评研究

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图书馆杂志 2024年第5期43卷 85-93,107页

作者：蒋辰袁曦临孙莉玲武秀枝东南大学图书馆

为加强高校图书馆阅读推广工作质量、量化评估服务效果,本研究以阅读推广服务中最基础的工作——主题书展为切入点,采用循证图书馆学(EBL)的理念进行效果测评设计,提出了一套系统有效的测评流程,并进行了验证。实证结果证明了此流程的... 详细信息

为加强高校图书馆阅读推广工作质量、量化评估服务效果,本研究以阅读推广服务中最基础的工作——主题书展为切入点,采用循证图书馆学(EBL)的理念进行效果测评设计,提出了一套系统有效的测评流程,并进行了验证。实证结果证明了此流程的有效性,为进一步优化和改进主题书展服务效果提供了最佳证据。本研究提供的案例剖析不仅可以作为高校图书馆主题书展效果测评方法进行推广,也可以给其他类型阅读推广服务的设置及优化提供路径参考和证据支持。

关键词：主题书展循证图书馆学 EBL 阅读推广

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Coevolution of superconductivity and Hall coefficient with anisotropic lattice shrinkage in compressed KCa_(2)Fe_(4)As_(24F_(2)

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Chinese Physics B 2024年第7期33卷 66-70页

作者：韩金宇洪文山蔡树赵金瑜郭静周亚洲王鹏玉曹立新罗会仟李世亮吴奇孙力玲 Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Center for High Pressure Science&Technology Advanced Research Beijing 100094China University of Chinese Academy of Sciences Beijing 100190China

The stability of superconductivity in superconductors is widely recognized to be determined by various factors,including charge,spin,orbit,lattice,and other related degrees of ***,we report our findings on the pressure-induced coevolution of superconductivity and Hall coefficient in KCa_(2)Fe_(4)As_(24F_(2),an iron-based superconductor possessing a hybrid crystal structure combining KFe_(2)As_(2) and *** investigation,involving high-pressure resistance,Hall effect and x-ray diffraction(XRD) measurements,allows us to observe the connection of the superconductivity and Hall coefficient with the anisotropic lattice *** find that its ambient-pressure tetragonal(T) phase presents a collapse starting at around 18 GPa,where the sign of the Hall coefficient(R_(H)) changes from positive to *** further compression,both superconducting transition temperature(T_(c)) and R_(H) exhibit a monotonous *** around 41 GPa,the superconductivity is completely suppressed(T_(c)=0),where the parameter a begins to decline again and the Hall coefficient remains nearly *** experiment results clearly demonstrate that the pressure-induced anisotropic lattice collapse plays a crucial role in tuning the interplay among multiple degrees of freedom in the superconducting system and,correspondingly,the stability of the superconductivity.

关键词： effects of pressure pnictides and chalcogenides transport properties

Evolution of Superconducting-Transition Temperature with Superfluid Density and Conductivity in Pressurized Cuprate Superconductors

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Chinese Physics Letters 2024年第4期41卷 110-117页

作者：赵金瑜蔡树陈逸雯顾根大闫宏涛郭静韩金宇王鹏玉周亚洲李延春李晓东任治安吴奇周兴江丁阳向涛毛河光孙力玲 Institute of Physics Chinese Academy of SciencesBeijing 100190China Center for High Pressure Science&Technology Advanced Research Beijing 100094China Condensed Matter Physics&Materials Science Department Brookhaven National LaboratoryNY 11973-5000USA University of Chinese Academy of Sciences Beijing 100190China Institute of High Energy Physics Chinese Academy of ScienceBeijing 100049China Beijing Academy of Quantum Information Sciences Beijing 100193China

What factors fundamentally determine the value of superconducting transition temperature Tc in high temperature superconductors has been the subject of intense *** the establishment of an empirical law known as Homes'law,there is a growing consensus in the community that the Tc value of the cuprate superconductors is closely linked to the superfluid density(ρ_(s))of its ground state and the conductivity(σ)of its normal ***,all the data supporting this empirical law(ρ_(s)=AσT_(c))have been obtained from the ambientpressure *** this study,we present the first high-pressure results about the connection of the quantities of ρ_(s) and σ with T_(c),through the studies on the Bi_(1.74)Pb_(0.38)Sr_(1.88)CuO_(6+δ)and Bi_(2)Sr_(2)CaCu_(2)O_(8+δ),in which the value of their high-pressure resistivity(ρ=1/σ)is achieved by adopting our newly established method,while the quantity ofρs is extracted using Homes'*** highlight that the Tc values are strongly linked to the joint response factors of magnetic field and electric field,i.e.,ρ_(s) and σ,respectively,implying that the physics determining T_(c) is governed by the intrinsic electromagnetic fields of the system.

关键词： superconductors Transition Conductivity

On the projective Ricci curvature

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Science China Mathematics 2021年第7期64卷 1629-1636页

作者： Zhongmin Shen liling sun Department of Mathematical Sciences Indiana University-Purdue University IndianapolisIndianapolisIN 46202USA Department of Mathematics Taiyuan University of TechnologyTaiyuan 030024China School of Science Jimei UniversityXiamen 361021China

The notion of the Ricci curvature is defined for sprays on a *** a volume form on a manifold,every spray can be deformed to a projective *** Ricci curvature of a projective spray is called the projective Ricci *** this paper,we introduce the notion of projectively Ricci-flat *** establish a global rigidity result for projectively Ricci-flat sprays with nonnegative Ricci *** we study and characterize projectively Ricci-flat Randers metrics.

关键词： spray Finsler metric Randers metric projective Ricci curvature

Discovery of Quantum Phase Transition in Pressurized Cuprate Superconductors

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Bulletin of the Chinese Academy of Sciences 2022年第1期36卷 45-46页

作者： sun liling Institute of Physics Chinese Academy of Sciences

The discovery of cuprate high-temperature superconductors in 1986 impacted science and technology considerably and continues to fascinate the communities of condensed matter physics and material sciences because they host the highest ambient-pressure superconducting transition temperature and unconventional electronic ***,the underlying mechanism of the superconductivity is yet an unsolved *** for the universal links between the superconducting state and its neighboring quantum states is believed to be an effective approach to elucidate the high-temperature superconducting mechanism.

关键词： mechanism. Transition neighboring

Weakly complex Einstein-Finsler vector bundle Dedicated to Professor Tongde Zhong for His 90th Birthday

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Science China Mathematics 2018年第6期61卷 1079-1088页

作者： liling sun Chunping Zhong College of Mathematics Taiyuan University of Technology Taiyuan 030024 China School of Mathematical Sciences Xiamen University Xiamen 361005 China

Let(E, F) be a complex Finsler vector bundle over a compact Khler manifold(M, g) with Khler form Φ. We prove that if(E, F) is a weakly complex Einstein-Finsler vector bundle in the sense of Aikou(1997),then it is modeled on a complex Minkowski space. Consequently, a complex Einstein-Finsler vector bundle(E, F) over a compact Khler manifold(M, g) is necessarily Φ-semistable and(E, F) =(E_1, F_1)⊕…⊕(E_k, F_k),where Fj := F |Ej, and each(Ej, Fj) is modeled on a complex Minkowski space whose associated Hermitian vector bundle is a Φ-stable Einstein-Hermitian vector bundle with the same factor c as(E, F).

关键词：向量 Minkowski Hermitian 生日歧管建模空格

No evidence of superconductivity in a compressed sample prepared from lutetium foil and H_(2)/N_(2) gas mixture

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Matter and Radiation at Extremes 2023年第4期8卷 76-80页

作者： Shu Cai Jing Guo Haiyun Shu Liuxiang Yang Pengyu Wang Yazhou Zhou Jinyu Zhao Jinyu Han Qi Wu Wenge Yang Tao Xiang Ho-kwang Mao liling sun Institute of Physics Chinese Academy of SciencesBeijing 100190China Center for High Pressure Science and Technology Advanced Research 100094 BeijingChina University of Chinese Academy of Sciences Beijing 100190China

A material described as lutetium–hydrogen–nitrogen(Lu-H-N in short)was recently claimed to have“near-ambient superconductivity”[Dasenbrock-Gammon et al.,Nature 615,244–250(2023)].If this result could be reproduced by other teams,it would be a major scientific ***,we report our results of transport and structure measurements on a material prepared using the same method as reported by Dasenbrock-Gammon et *** x-ray diffraction measurements indicate that the obtained sample contains three substances:the facecentered-cubic(FCC)-1 phase(Fm-3m)with lattice parameter a=5.03Å,the FCC-2 phase(Fm-3m)with a lattice parameter a=4.755Å,and Lu *** two FCC phases are identical to the those reported in the so-called near-ambient ***,we find from our resistance measurements in the temperature range from 300 K down to 4 K and the pressure range 0.9–3.4 GPa and our magnetic susceptibility measurements in the pressure range 0.8–3.3 GPa and the temperature range down to 100 K that the samples show no evidence of *** also use a laser heating technique to heat a sample to 1800 XC and find no superconductivity in the produced dark blue material below 6.5 *** addition,both samples remain dark blue in color in the pressure range investigated.

关键词： resistance superconductivity ambient