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Imaging momentum-space Cooper pair formation and its competition with the charge density wave gap in a kagome superconductor

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 142-150页

作者： Yiming Sun yubing Tu Yang Luo Shuikang Yu Hongyu Li Yunmei Zhang Ping Wu Zhuying Wang fan Zhang Wanru Ma Zuowei Liang Jianjun Ying Tao Wu Ziji Xiang Junfeng He Lei Shan Zhenyu Wang Xianhui Chen Department of Physics CAS Key Laboratory of Strongly Coupled Quantum Matter Physicsand Hefei National LaboratoryUniversity of Science and Technology of ChinaHefei 230026China Information Materials and Intelligent Sensing Laboratory of Anhui Province Institutes of Physical Science and Information TechnologyAnhui UniversityHefei 230601China Collaborative Innovation Center of Advanced Microstructures Nanjing 210093China

The superconducting ground state of kagome metals AV_(3)Sb_(5)(where A stands for K,Rb,or Cs)emerges from an exotic charge density wave(CDW)state that potentially breaks both rotational and time reversal ***,the specifics of the Cooper pairing mechanism,and the nature of the interplay between these two states remain elusive,largely due to the lack of momentum-space(k-space)superconducting energy gap *** implementing Bogoliubov quasiparticle interference(B QPI)imaging,we obtain k-space information on the multiband superconducting gap structureΔ_(SC)^(i)(k)in pristine CsV_(3)Sb_(5).We show that the estimated energy gap on the vanadium d_(xy/x^(2)-y^(2))orbital is anisotropic but nodeless,with a minimal value located near the M ***,a comparison ofΔ_(SC)^(i)(k)with the CDW gapΔ_(CDW)^(i)(k)obtained by angle-re solved photoemission spectro scopy(ARPES)reveals direct k-space competition between the se two order parameters,i.e.,the opening of a large(small)CDW gap at a given momentum corresponds to a small(large)superconducting *** the long-range CDW order is suppressed by replacing vanadium with titanium,we find a nearly isotropic energy gap on both the V and Sb *** information will be critical for identifying the microscopic pairing mechanism and its interplay with intertwined electro nic orders in this kagome superconductor family.

关键词： kagome lattice charge density wave superconducting energy gap scanning tunneling microscopy

在草业科学专业开展农业伦理教学的特殊性研究——“任继周草地农业学术思想研讨会”之“农业伦理教学研讨会”侧记

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科学．经济．社会 2023年第6期41卷 9-14页

作者：赵安范玉兵兰州大学草地农业科技学院

任继周草地农业与农业伦理思想之间具有深刻的逻辑关系,草业科学专业是农业伦理教学的第一块试验田和最好的实践基地,农业伦理学也要内化于草业等农业科学之中,为开拓草业科学专业师生的人文视野提供最优教材。这是在草业科学专业开展... 详细信息

任继周草地农业与农业伦理思想之间具有深刻的逻辑关系,草业科学专业是农业伦理教学的第一块试验田和最好的实践基地,农业伦理学也要内化于草业等农业科学之中,为开拓草业科学专业师生的人文视野提供最优教材。这是在草业科学专业开展农业伦理教学与科研得天独厚的优势。

关键词：任继周草业科学农业伦理教学研讨会

Bi_(2)WO_(6)/AgInS_(2)S-scheme heterojunction:Efficient photodegradation of organic pollutant and toxicity evaluation

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Journal of Materials Science & Technology 2024年第3期170卷 200-211页

作者： Yanyan Zhao Xu fan Hongxing Zheng Enzhou Liu Jun fan Xuejun Wang College of Biology Pharmacy and Food Engineering Shangluo UniversityShangluo 726000China QinLing-Bashan Mountains Bioresources Comprehensive Development C.I.C. Shaanxi University of TechnologyHanzhong 723001China School of Chemical Engineering Northwest UniversityXi’an 710069China

Constructing of heterojunction was identified as a feasible way to improve photocatalytic activity of *** this work,a n-p type Bi_(2)WO_(6)/AgInS_(2)S-scheme heterojunction was successfully prepared for organic pollutants *** Bi_(2)WO_(6)/AgInS_(2)S-scheme heterojunction exhibited much higher pho-tocatalytic activity towards Rhodamine B(92.24%,expose to visible light for 60 min),norfloxacin(81.73%,expose to visible light for 90 min)and levofloxacin(87.46%,expose to visible light for 90 min)than pure Bi_(2)WO_(6)and pure AgInS_(2).Toxicity analysis indicated the low environmental toxicity of Rhodamine B degradation intermediates for Rye seeds and Sudangrass seeds germination and *** study displayed that AgInS_(2)and Bi_(2)WO_(6)work as the primary photocatalyst to form·O_(2)−and ·OH,*** improved photocatalytic activity of the Bi_(2)WO_(6)/AgInS_(2)S-scheme heterojunction was due to the im-proved light response range and intensified carrier separation ***,a S-scheme charge transfer mechanism including multiple charge transfer channels was *** work could provide an effective strategy for organic pollutants degradation in wastewater.

关键词： Photocatalysis S-scheme heterojunction AgInS_(2) Bi_(2)WO_(6) Toxicity experiments

Soliton resolution and asymptotic stability of N-solutions for the defocusing Kundu–Eckhaus equation with nonzero boundary conditions

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Communications in Theoretical Physics 2024年第1期76卷 1-6页

作者： Engui fan Yanxi Zhang School of Mathematical Sciences and Key Laboratory of Mathematics for Nonlinear Science Fudan UniversityShanghai200433China Tianjin Xinhua High School No.99 machang RoadTianjin300204China

In this paper,we address interesting soliton resolution,asymptotic stability of N-soliton solutions and the Painleve asymptotics for the Kundu-Eckhaus(KE)equation with nonzero boundary conditions iq_(t)+q_(xx)-2(l|q|^(2)-1)q+4β^(2)(lql^(4)-1)q+4iβ(lql^(2))_(x)q=0,q(x,0)=q_(0)(x)-±1,x→±∞.The key to proving these results is to establish the formulation of a Riemann-Hilbert(RH)problem associated with the above Cauchy problem and find its connection with the RH problem of the defocusing NLS *** the■-steepest descent method and the results of the defocusing NLS equation,we find complete leading order approximation formulas for the defocusing KE equation on the whole(x,t)half-plane including soliton resolution and asymptotic stability of N-soliton solutions in a solitonic region,Zakharov-Shabat asymptotics in a solitonless region and the Painlevéasymptotics in two transition regions.

关键词： defocusing Kundu-Eckhaus equation Riemann-Hilbert problems steepest descent method soliton resolution asymptotic stability Painleve transcendents

Existence of Global Solutions to the Nonlocal mKdV Equation on the Line

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Chinese Annals of Mathematics,Series B 2024年第4期45卷 497-528页

作者： Anran LIU Engui fan School of Mathematical Sciences Fudan University

In this paper, the authors address the existence of global solutions to the Cauchy problem for the integrable nonlocal modified Korteweg-de Vries（nonlocal mKdV for short） equation under the initial data u0 ∈ H3（R） ∩H1,1（R） with the L1（R） small-norm assumption. A Lipschitz L2-bijection map between potential and reflection coefficient is established by using inverse scattering method based on a Riemann-Hilbert problem associated with the Cauchy problem. The map from initial potential to reflection coefficient is obtained in direct scattering transform. The inverse scattering transform goes back to the map from scattering coefficient to potential by applying the reconstruction formula and Cauchy integral operator. The bijective relation naturally yields the existence of global solutions in a Sobolev space H3（R） ∩ H1,1（R） to the Cauchy problem.

关键词： Global solutions Lipschitz continuous Nonlocal mKdV equation Plemelj projection operator Riemann-Hilbert problem

Drogue detection for autonomous aerial refueling via hybrid pigeon-inspired optimized color opponent and saliency aggregation

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Chinese Journal of Aeronautics 2024年第5期37卷 27-38页

作者： Tongyan WU Haibin DUAN Yanming fan State Key Laboratory of Virtual Reality Technology and Systems School of Automation Science and Electrical EngineeringBeihang UniversityBeijing 100083China Virtual Reality Fundamental Research Laboratory Department of Mathematics and TheoriesPeng Cheng LaboratoryShenzhen 518000China AVIC Shenyang Aircraft Design and Research Institute Shenyang 110035China

Drogue detection is one of the challenging tasks in autonomous aerial refueling due to the requirement for accuracy and *** detection based on image intrinsic cues can achieve fast detection,but with poor *** studies reveal that optimization-based methods provide accurate and quick solutions for saliency *** paper presents a hybrid pigeon-inspired optimization method,the optimized color opponent,that aims to adjust the weight of color opponent channels to detect the drogue *** can optimize the weights in the selected aerial refueling scene offline,and the results are applied for drogue detection in the scene.A novel algorithm aggregated by the optimized color opponent and robust background detection is presented to provide better precision and *** results on benchmark datasets and aerial refueling images show that the proposed method successfully extracts the saliency region or drogue and exhibits superior performance against the other saliency detection methods with intrinsic *** algorithm designed in this paper is competent for the drogue detection task of autonomous aerial refueling.

关键词： Autonomous aerial refueling Drones Hybrid pigeon-inspired optimization Color opponent Saliency detection Saliency aggregation

Experimental Study on Wire Melting Control Ability of Twin-Body Plasma Arc

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 184-194页

作者： Ruiying Zhang fan Jiang Long Xue School of Mechanical Engineering Beijing Institute of Petrochemical TechnologyBeijing 102617China Beijing Academy of Safety Engineering and Technology Beijing 102617China College of Mechanical and Energy Engineering Beijing University of TechnologyBeijing 100124China

The twin-body plasma arc has the decoupling control ability of heat transfer and mass transfer,which is beneficial to shape and property control in wire arc additive *** this paper,with the wire feeding speed as a characteristic quantity,the wire melting control ability of twin-body plasma arc was studied by adjusting the current separation ratio(under the condition of a constant total current),the wire current/main current and the position of the wire in the arc axial *** results showed that under the premise that the total current remains unchanged(100 A),as the current separation ratio increased,the middle and minimum melting amounts increased approximately synchronously under the effect of anode effect power,the first melting mass range remained constant;the maximum melting amount increased twice as fast as the middle melting amount under the effect of the wire feeding speed,and the second melting mass range was *** the wire current increased,the anode effect power and the plasma arc power were both factors causing the increase in the wire melting amount;however,when the main current increased,the plasma arc power was the only factor causing the increase in the wire melting *** average wire melting increment caused by the anode effect power was approximately 2.7 times that caused by the plasma arc *** minimum melting amount was not affected by the wire-torch distance under any current separation ratio *** the current separation ratio increased and reached a threshold,the middle melting amount remained constant with increasing wire-torch *** the current separation ratio continued to increase and reached the next threshold,the maximum melting amount remained constant with the increasing wire-torch *** effect of the wire-torch distance on the wire melting amount reduced with the increase in the current separation *** this study,the decoupling mechanism and ability of this innovative

关键词： Twin-body plasma arc Melting control ability Melting amount Current separation ratio

Processing,microstructure,and properties of porous ceramic composites with directional channels

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Journal of Materials Science & Technology 2024年第1期168卷 1-15页

作者： Bo Zhang Yang Yang Xueling fan Key Laboratory of Service Performance and Protection Technology in Extreme Environments Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory for Strength and Vibration of Mechanical Structures School of Aerospace EngineeringXi’an Jiaotong UniversityXi’an 710049China

Porous ceramic composites with directional microchannels from micrometer to dozens of micrometer levels have attracted more and more attention in various fields including aerospace,biomedicines,and thermal insulation due to their excellent fluid permeability,mechanical properties,*** this article,we summarize the recent directional porous ceramics developments including their main processing routes and respective ***,the properties get from different processing routes have been com-pared and analyzed in terms of microstructures,mechanical properties,and *** has been given to the deeper understanding which can allow one to control the microstructural features of these porous ceramic composites to obtain the desired *** work can provide a useful reference for the development and application of porous ceramic composites with directional microchan-nels.

关键词： Porous ceramic composites Directional microchannels Processing routes Permeability

Flow instability of supercritical hydrocarbon fuel in a multi-channel cooling system

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Chinese Journal of Aeronautics 2024年第2期37卷 283-295页

作者： Yichao JIN Kun WU Xuejun fan Institute of Applied Physics and Computational Mathematics Beijing 100094China Institute of Mechanics Chinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

Thermally-induced flow instabilities are a critical issue in multi-channel regenerative cooling *** particular,the interactions between Density-Wave Oscillations(DWO)and Flow Maldistribution(FMD)can result in complex and disastrous instability *** study investigates the instability behaviors of hydrocarbon fluid in a four-channel system with a constant heat flux ratio using both frequency-and time-domain *** the heat flux increases,the in-tube flow sequentially destabilizes in each channel and converges to new equilibrium states,leading to the emergence of FMD *** also causes the system eigenvalue to change repeatedly from negative to positive rather than increasing ***,the system eigenvalues are between those of the two most unstable channels,indicating that the stability behavior of the entire system is dictated by the most unstable *** FMD occurs,flow oscillations are activated in channels with weak stability,and the in-tube flow is observed to evolve into various flow patterns,including stable flow,self-sustained oscillation,oscillation divergence,quasiperiodic oscillation,and oscillation *** novel instability mode of oscillation excursion involves a spontaneous transition of operating *** oscillates from an equilibrium state and then stabilizes at a new operational state after oscillation-induced ***,the newfound stable state may also be only temporary,with the in-tube flow regressing to the initial state,resulting in quasi-periodic oscillation.

关键词： Cooling Supercritical fluids Hydrocarbons Flow instability Flow maldistribution Density-wave oscillations