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Anti-parity-time symmetric phase transition in diffusive systems

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Chinese Physics B 2021年第3期30卷 9-16页

作者： Pei-Chao Cao xue-feng zhu School of Physics and Innovation Institute Huazhong University of Science and TechnologyWuhan 430074China

Parity-time (PT) symmetry/anti-parity-time (APT) symmetry in non-Hermitian systems reveal profound physics andspawn intriguing effects. Recently, it has been introduced into diffusive systems together with the concept of exceptionalpoints (EPs) from quantum mechanics and the wave systems. With the aid of convection, we can generate complex thermalconductivity and imitate various wavelike dynamics in heat transfer, where heat flow can be “stopped” or moving against thebackground motion. Non-Hermitian diffusive systems offer us a new platform to investigate the heat wave *** this review, we first introduce the construction of APT symmetry in a simple double-channel toy model. Then we showthe phase transition around the EP. Finally, we extend the double-channel model to the four-channel one for showing thehigh-order EP and the associated phase transition. In a general conclusion, the phase difference of adjacent channels isalways static in the APT symmetric phase, while it dynamically evolves or oscillates when the APT symmetry is broken.

关键词： anti-parity-time symmetry phase transition exceptional point heat transfer

Phase-Locking Diffusive Skin Effect

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Chinese Physics Letters 2022年第5期39卷 94-99页

作者： Pei-Chao Cao Yu-Gui Peng Ying Li xue-feng zhu School of Physics and Innovation Institute Huazhong University of Science and TechnologyWuhan 430074China Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical InstrumentationZJU-Hangzhou Global Scientifc and Technological Innovation CenterZhejiang UniversityHangzhou 310027China International Joint Innovation Center Key Laboratory of Advanced Micro/Nano Electronic Devices&Smart Systems of ZhejiangThe Electromagnetics Academy at Zhejiang UniversityZhejiang UniversityHaining 314400China Jinhua Institute of Zhejiang University Zhejiang UniversityJinhua 321099China

We explore the exceptional point(EP)induced phase transition and amplitude/phase modulation in thermal diffusion *** start from the asymmetric coupling double-channel model,where the temperature field is unbalanced in the amplitude and locked in the symmetric *** extending into the one-dimensional tight-binding non-Hermitian lattice,we study the convection-driven phase locking and the asymmetric-couplinginduced diffusive skin effect with the high-order EPs in static *** convection and asymmetric couplings,we further show the phase-locking diffusive skin *** work reveals the mechanism of controlling both the amplitude and phase of temperature fields in thermal coupling systems and has potential applications in non-Hermitian topology in thermal diffusion.

关键词： effect coupling asymmetric

Acoustic topological adiabatic passage via a level crossing

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Science China(Physics,Mechanics & Astronomy) 2021年第4期64卷 2-9页

作者： Ya-Xi Shen Long-Sheng Zeng Zhi-Guo Geng De-Gang Zhao Yu-Gui Peng Jie zhu xue-feng zhu School of Physics and Innovation Institute Huazhong University of Science and TechnologyWuhan 430074China Department of Mechanical Engineering Hong Kong Polytechnic UniversityHong KongChina Hong Kong Polytechnic University Shenzhen Research Institute Shenzhen 518057China

Stimulated adiabatic passage has been extensively studied to achieve robust and selective population transfer in quantum systems. Recently, the quantum-classic analogy has been rapidly developing and can be considered responsible for the implementation of the adiabatic transfer of sound energy in cavity chain systems. In this article, we investigate the adiabatic transfer of sound energy between two topological end states in the Su-Schrieffer-Heeger(SSH) cavity chain, which can be considered to be the acoustic analog of the quantum chirped-pulse excitation. The topological adiabatic passage in SSH cavity chain has two categories. When the single-cavity resonance frequencies on the sublattices A and B in the SSH cavity chain do not switch their spectrum positions, the topologically protected adiabatic evolution results in the returning passage of the sound excited in one end cavity. When a level crossing with single-cavity resonance frequencies on the sublattices A and B exhibits switch in the frequency spectrum, acoustic energy is observed to be topologically pumped between the two end cavities of the SSH chain.

关键词： acoustic adiabatic passage topological end state level crossing

Microstructural evolutions of Cu(Ni)/AuSn/Ni joints during reflow

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Progress in Natural Science:Materials International 2011年第4期21卷 347-354页

作者： Xiao-feng WEI,Ri-chu WANG,Chao-qun PENG,Yan feng,xue-wei zhu School of Materials Science and Engineering,Central South University,Changsha 410083,China School of Materials Science and Engineering Central South University Changsha 410083 China

Interfacial reactions of the Ni/AuSn/Ni and Cu/AuSn/Ni joints are experimentally studied at 330℃for various reflow *** microstructures and mechanical properties of the as-solidified solder joints are *** as-solidified solder matrix of Ni/AuSn/Ni presents a typical eutecticξ-(Au,Ni)5Sn+δ-(Au,Ni)Sn lamellar microstructure after reflow at 330℃for 30 *** reflow for 60 s,a thin and flat(Ni,Au)3Sn2intermetallic compound(IMC) layer is formed,and some needle-like(Ni,Au)3Sn2phases grow from the IMC layer into the solder *** the other hand,a cellular-typeξ(Cu) layer is found at the upper AuSn/Cu interface in the Cu/AuSn/Ni joint after reflow for 30 s,and a(Ni,Au,Cu)3Sn2IMC layer is also formed at the lower AuSn/Ni interface. For both joints the IMC layer grows significantly with the increase of reflow time,but the growth rate of(Ni,Au,Cu)3Sn2IMC in the Cu/AuSn/Ni joint is smaller than that of the(Ni,Au)3Sn2layer in the Ni/AuSn/Ni *** comparisons of the shear strength and fracture surface between the Ni/AuSn/Ni and Cu/AuSn/Ni joints suggest that the coupling effect of the Cu/AuSn/Ni sandwich joint is helpful to prevent the excessive growth of(Ni,Au)3Sn2,which in turn enhances the mechanical reliability of the solder joint.

关键词： Cu(Ni)/AuSn/Ni joints interfacial reaction intermetallic compound(IMC) coupling effect

STUDIES　ON　THE　SYNTHESIS　AND　REACTIONS　OF　N－（1－OXO－4－CARBONYL－2，6，7－TRIOXA－1－PHOSPHABICYCLO　［2．2．2］　OCTANE）－N＇－ARYL　THIOUREAS

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Chinese Chemical Letters 1995年第1期6卷 19-22页

作者： Yu Gui LI xue feng zhu Institute of Elemento-Organic Chemistry, Nanka i University,Tianjin, 300071 Nankai Univ Inst Elementoorgan Chem Tianjin 300071 Peoples R China

N- (1 -oxo-4-carbony 1-2. 6, 7- trioxa- 1 -phosphabicyclo[2. 2. 2] octane) - N- aryl thioureas (4)were syntbesized in this paper. (4) reacted,with AgNO3-H2O and chloroacetyl cblor ide to afford the corresponding urea herivatives (5) and cycli- zed produets (10), respectively, The mechanism of desulphurisation of (4) bas also been studied.

关键词： OXO CARBONYL OF REACTIONS ARYL AND

Influence of pouring methods on filling process,microstructure and mechanical properties of AZ91 Mg alloy pipe by horizontal centrifugal casting

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China Foundry 2018年第3期15卷 196-202页

作者： xue-feng zhu Bao-yi Yu Li Zheng Bo-ning Yu Qiang Li Shu-ning Lü Hao Zhang School of Materials Science and Engineering Shenyang University of Technology

Pouring position as the input heat source has great infl uence on the temperature fi eld evolution. In this study, the Flow3 D simulation software was applied to investigate the infl uence of pouring methods(with fi xed or moving pouring channel) on AZ91 Mg alloy horizontal centrifugal casting(HCC) process. The simulation results show that the moving pouring channel method can effectively increase the cooling rate and formability of casting pipe. The casting experiment shows that an AZ91 Mg alloy casting pipe with homogeneous microstructure and clear contour was obtained by the moving pouring channel method, and the grain size of the casting pipe is signifi cantly decreased. Meanwhile, serious macro-segregation appeared in the AZ91 casting pipe by the fi xed pouring channel HCC process. Compared with the fi xed pouring channel, the moving pouring channel can remarkably improve the ultimate tensile strength and elongation of the AZ91 HCC pipe from 142.2 MPa to 201.5 MPa and 6.2% to 6.7%, respectively.

关键词： horizontal centrifugal casting (HCC) numerical simulation pouring method AZ91Mg alloy

Probability-Density-Based Deep Learning Paradigm for the Fuzzy Design of Functional Metastructures

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Research 2020年第1期2020卷 1637-1647页

作者： Ying-Tao Luo Peng-Qi Li Dong-Ting Li Yu-Gui Peng Zhi-Guo Geng Shu-Huan Xie Yong Li Andrea Alù Jie zhu xue-feng zhu School of Physics and Innovative Institute Huazhong University of Science and TechnologyWuhan 430074China Institute of Acoustics Tongji UniversityShanghai 200092China Photonics Initiative Advanced Science Research CenterCity University of New York85 St.Nicholas TerraceNew YorkNY 10031USA Department of Mechanical Engineering Hong Kong Polytechnic UniversityHong Kong SARChina Hong Kong Polytechnic University Shenzhen Research Institute Shenzhen 518057China

In quantum mechanics,a norm-squared wave function can be interpreted as the probability density that describes the likelihood of a particle to be measured in a given position or *** statistical property is at the core of the fuzzy structure of ***,hybrid neural structures raised intense attention,resulting in various intelligent systems with farreaching ***,we propose a probability-density-based deep learning paradigm for the fuzzy design of functional *** contrast to other inverse design methods,our probability-density-based neural network can efficiently evaluate and accurately capture all plausible metastructures in a high-dimensional parameter *** maxima in probability density distribution correspond to the most likely candidates to meet the desired *** verify this universally adaptive approach in but not limited to acoustics by designing multiple metastructures for each targeted transmission spectrum,with experiments unequivocally demonstrating the effectiveness and generalization of the inverse design.

关键词： inverse Probability acoustics

Orientation Angle of Molecules at Hexadecane-Water Interface Studied with Total Internal Reflection Second Harmonic Generation

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Chinese Journal of Chemical Physics 2016年第6期29卷 650-656,I0001页

作者： Li-bo Zhang Hui Fang Shun-li Chen xue-feng zhu Wei Gan LaboratoryofEnvironmentalScienceandTechnology TheXinjiangTechnicalInstituteofPhysicsChemistryKeyLaboratoryofFunctionalMaterialsandDevicesforSpecialEnvironmentsChineseAcademyofSciencesUrumqi830011China UniversityofChineseAcademyofSciences Beijing100049China

The orientation angle is an important parameter that reflects the structure of molecules at interfaces. In order to obtain this parameter, second order nonlinear spectroscopic techniques including second harmonic generation （SHG） and sum frequency generation-vibrational spec- troscopy （SFG-VS） have been successfully applied through analysis of the nonlinear signal from various polarizations. In some SHG and SFG-VS experiments, total internal reflection （TIR） configuration has been adopted to get enhanced signals. However, the reports on the detailed procedure of the polarization analysis and the calculation of the orientation angle of interracial molecules under TIR configuration are still very few. In this paper, we mea- sured the orientation angles of two molecules at the hexadecane-water interface under TIR and Non-TIR experimental configurations. The results measured from polarization analysis in TIR configuration consist with those obtained from Non-TIR configuration. This work demonstrates the feasibility and accuracy of polarization analysis in the determination of the orientation angle of molecules at the interfaces under TIR-SHG configuration.

关键词： Second harmonic generation Total internal reflection Hyperpolarizability Polarization Orientation angle

Order-Disorder Transition of Carboxyl Terminated Chains in Polydiacetylenes Vesicles Probed by Second Harmonic Generation and Two-Photon Fluorescence

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Chinese Journal of Chemical Physics 2018年第3期31卷 269-276,367页

作者： Shun-li Chen xue-feng zhu Fang-yuan Yang xue-cong Pan Wei Gan Qun-hui Yuan Laboratory of Environmental Science and Technology Xinjiang Technical Institute of Physics and ChemistryKey Laboratory of Functional Materials and Devices for Special EnvironmentsChinese Academy of SciencesUrumqi 830011China School of Sciences Harbin Institute of Technology(Shenzhen)Shenzhen 518055China School of Materials Science and Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China

To understand and control the interfacial properties of polydiacetylenes(PDAs)vesicles withπ-conjugated backbone is very important for their colorimetric sensing of chemical and biological *** this work,we adopted 10,12-pentacosadiynoic acid(PCDA)as the model molecule to prepare PDAs vesicles in aqueous solution with different forms(from monomer to blue-to-purple-to-red phase)by controlling the UV irradiation *** variations of the interfacial conformation of PDAs vesicles during chromatic transitions were inspected by the adsorption behaviors of probe molecules(4-(4-diethylaminostyry)-1-methylpyridinium iodide,D289)on vesicle surface with surface-specific second harmonic generation(SHG)and zeta potential *** SHG signal from D289 adsorbed on vesicle surface attenuated sharply,and the adsorption free energy as well as the corresponding two-photon fluorescence signal decreased slightly in chromatic ***,the change in the surface density of the adsorbed D289 molecules for PDAs vesicles with different forms was relatively small as estimated from zeta potential *** attenuation of the SHG intensity was thus attributed to the overall order-disorder transition and the changed orientation of D289 molecules caused by the gradual distortion of carboxyl head group driven by backbone perturbation.

关键词： Polydiacetylenes vesicle Polymerization interfacial adsorption Second harmonic generation Order-disorder transition