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Topological magnetoelectric response in ferromagnetic axion insulators

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National Science Review 2024年第2期11卷 8-14页

作者： Yuhao Wan jiayu li Qihang liu Department of Physics and Shenzhen Institute for Quantum Science and Engineering(SIQSE) Southern University of Science and Technology Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices Southern University of Science and Technology Guangdong Provincial Key Laboratory for Computational Science and Material Design Southern University of Science and Technology

The topological magnetoelectric effect （TME） is a hallmark response of the topological field theory,which provides a paradigm shift in the study of emergent topological ***,its direct observation is yet to be realized due to the demanding magnetic configuration required to gap all surface ***,we theoretically propose that axion insulators with a simple ferromagnetic configuration,such as the MnBi2Te4/（Bi2Te3）nfamily,provide an ideal playground to realize the *** the designed triangular prism geometry,all the surface states are magnetically *** a vertical electric field,the surface Hall currents give rise to a nearly half-quantized orbital moment,accompanied by a gapless chiral hinge mode circulating in ***,the orbital magnetization from the two topological origins can be easily distinguished by reversing the electric *** work paves the way for direct observation of the TME in realistic axion-insulator materials.

关键词： topological magnetoelectric effect axion insulator magnetic topological materials

Generalized Symplectic Mean Curvature Flows in Almost Einstein Surfaces

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Chinese Annals of Mathematics,Series B 2014年第1期35卷 33-50页

作者： jiayu li liuqing YANG School of Mathematical Sciences University of Science and Technology of China Academy of Mathematics and Systems Science Chinese Academy of Sciences

The authors mainly study the generalized symplectic mean curvature flow in an almost Einstein surface,and prove that this flow has no type-I *** the graph case,the global existence and convergence of the flow at infin... 详细信息

关键词： Almost Einstein Symplectic mean curvature flow Singularity Minimalsurface

Regularity and Compactness of Stationary Map-Varifold Pairs

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Chinese Annals of Mathematics,Series B 2023年第6期44卷 929-944页

作者： jiayu li Jie ZHOU Chaona ZHU School of Mathematical Sciences University of Science and Technology of ChinaHefei 230026China School of Mathematical Sciences Capital Normal UniversityBeijing 100148China School of Mathematics and Statistics Ningbo UniversityNingbo 315211ZhejiangChina

The authors introduce the conception of stationary map-varifold pairs and prove a compactness *** applications,they analyse the asymptotic structure of the pseudo tangent map of stationary harmonic *** stationary pair,they also get a strong convergence criterion about the map part and introduce the stratification of the singular set.

关键词： Stationary map-varifold pairs Regularity Compactness

The boundary value problem for the mean field equation on a compact Riemann surface

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Science China Mathematics 2023年第1期66卷 115-142页

作者： jiayu li linlin Sun Yunyan Yang School of Mathematical Sciences University of Science and Technology of ChinaHefei 230026China School of Mathematics and Statistics Wuhan UniversityWuhan 430072China School of Mathematics Renmin Universityof ChinaBeijing100872China

Let(Σ,g)be a compact Riemann surface with smooth boundary■Σ,Δ_(g) be the Laplace-Beltrami operator,and h be a positive smooth *** a min-max scheme introduced by Djadli and Malchiodi(2008)and Djadli(2008),we prove that ifΣis non-contractible,then for anyρ∈(8kπ,8(k+1)π)with k∈N^(*),the mean field equation{Δgu=ρhe^(u)/∫∑he^(u)dv_(g)in∑,u=0 on■∑has a *** generalizes earlier existence results of Ding et al.(Ann Inst H PoincaréAnal Non linéaire,1999)and Chen and lin(2003)in the Euclidean *** we consider the corresponding Neumann boundary value *** h is a positive smooth function,then for anyρ∈(4kπ,4(k+1)π)with k∈N^(*),the mean field equation{Δgu=ρhe^(u)/∫_(∑)he^(u)dv_(g)-1/|∑|in∑,■u/■v=0 on■∑has a solution,where v denotes the unit normal outward vector on ■Σ.Note that in this case we do not require the surface to be non-contractible.

关键词： mean field equation topological method min-max scheme

Edge detection on terahertz pulse imaging of dehydrated cutaneous malignant melanoma embedded in paraffin

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Frontiers of Optoelectronics 2019年第3期12卷 317-323页

作者： jiayu li Yijun XIE Ping SUN Beijing Key Laboratory of Applied Optics Department of PhysicsBeijing Normal UniversityBeijing 100875China

Terahertz pulse imaging of cutaneous malignant melanoma dehydrated by ethanol and embedded in paraffin was carried out across a frequency range of 0.2- 1.4 THz. First, the tissue images based on the time-domain electric-field amplitude information were acquired. Then the areas of normal and cancerous tissues were determined using multi-scale, multi-azimuth and multi-structural element mathematical morphology. The physical meaning of the image was analyzed by calculation of the refractive index and absorption coefficient of cutaneous malignant melanoma in different areas. The refractive index of both normal and cancerous tissues showed anomalous dispersion. The refractive index of cancerous tissues tended to vary between 0.2 and 0.7 THz, while that of normal and fat tissues remain almost unchanged. The absorption of cancerous tissues was higher, with a maximum at 0.37 THz. We concluded that both the refractive index and absorption coefficient differ considerably between normal and cancerous tissues, and the areas of normal and abnormal tissues can be identified using THz pulse imaging combined with mathematical morphology. The method for edge detection of terahertz pulse imaging of cutaneous malignant melanoma provides a reference for the safe surgical removal of malignant tumors.

关键词： terahertz pulse imaging edge detection mathematical morphology cutaneous malignant melanoma refractive index absorption coefficient

The Second Type Singularities of Symplectic and Lagrangian Mean Curvature Flows

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Chinese Annals of Mathematics,Series B 2011年第2期32卷 223-240页

作者： Xiaoli HAN jiayu li Jun SUN Department of Mathematical Sciences Tsinghua University Beijing 100084 China Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

This paper mainly deals with the type II singularities of the mean curvature flow from a symplectic surface or from an almost calibrated Lagrangian surface in a K¨ahler *** relation between the maximum of the Kahler angle and the maximum of |H|2 on the limit flow is *** authors also show the nonexistence of type II blow-up flow of a symplectic mean curvature flow which is normal flat or of an almost calibrated Lagrangian mean curvature flow which is flat.

关键词： Symplectic surface Lagrangian surface Mean curvature flow

A Note on Curvature Estimate of the Hermitian–Yang–Mills Flow Dedicated to celebrate the Sixtieth anniversary of USTC

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Communications in Mathematics and Statistics 2018年第3期6卷 319-358页

作者： jiayu li Chuanjing Zhang Xi Zhang School of Mathematical Sciences University of Science and Technology of ChinaHefei 230026People’s Republic of China AMSS CASBeijing 100080People’s Republic of China

In this paper,we study the curvature estimate of the Hermitian–Yang–Mills flow on holomorphic vector *** one simple case,we show that the curvature of the evolved Hermitian metric is uniformly bounded away from the ... 详细信息

关键词： Holomorphic structure Harder-Narasimhan-Seshadri filtration Hermitian-Yang-Mills flow

Design of hexagon microstrip antenna for vehicle-to-vehicle communication

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The Journal of China Universities of Posts and Telecommunications 2016年第4期23卷 69-76页

作者： Hao Honggang li jiayu Huang Daili Luo Wei College of Photoelectric Engineering Chongqing University of Posts and Telecommunications

Considering the shortcomings of the existing vehicle-to-vehicle（V2V） communication antennas, this paper proposes a regular hexagon broadband microstrip antenna. By loading shorting pins and etching V-shape slots with different size at each angle of the regular hexagon patch, it realizes impedance matching and obtains better impedance bandwidth. The simulated results show that the relative bandwidth of this antenna reaches 35.55%, covers the frequency band of 4.74 GHz to 6.79 GHz. The antenna acquires an omni-directional radiation pattern in the horizontal plane whose out of roundness is less than 0.5 d B. In addition, the antenna is manufactured and tested, whose tested results are basically consistent with simulated results. Because the height of antenna is 3 mm, it is easy to be hidden on roof of a vehicle for V2 V communication.

关键词： regular hexagon microstrip antenna shorting pins V-shape slots omni-directional radiation pattern V2V communication

Phthalocyanine-derived catalysts decorated by metallic nanoclusters for enhanced CO_(2)electroreduction

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Green Energy & Environment 2023年第2期8卷 444-451页

作者： Jiacheng Chen jiayu li Jing Xu Minghui Zhu Yi-Fan Han State Key Laboratory of Chemical Engineering School of Chemical EngineeringEast China University of Science and TechnologyShanghai200237China

Electrochemical CO_(2)reduction(CO_(2)RR)over molecular catalysts is a paramount approach for CO_(2)conversion to ***,we report a novel phthalocyanine-derived catalyst synthesized by a two-step method with a much improved ***,the catalyst contains both Ni-N4sites and highly dispersed metallic Ni nanoclusters,leading to an increased CO_(2)RR currents by two *** labelling study and in situ spectroscopic analysis demonstrate that the existence of metallic Ni nanoclusters is the key factor for the activity enhancement and can shift the CO_(2)RR mechanism from being electron transfer(ET)-limited(forming*COO^(-))to concerted proton-electron transfer(CPET)-limited(forming CO).

关键词： Carbon dioxide Electroreduction Hybrid catalyst Nickel-based catalysts Mechanism