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9th International Conference on Advanced Materials Research, ICAMR 2019

作者： Zhu, Changfeng Zheng, Zhijun Wang, Shilong Zhao, Kai Yu, Jilin CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics University of Science and Technology of China Hefei230026 China School of Civil Engineering Anhui University of Technology Maanshan243032 China

ISBN: (纸本)9783035714845

The self-similar isotropic hardening model developed by Deshpande and Fleck has been widely used. An important issue in this model is to determine the value of ellipticity. The ellipticity was treated as a constant in the subsequent yield, but different values were suggested in the literature. In this paper a cell-based finite element model based on the 3D Voronoi technique is used to verify the Deshpande-Fleck foam model. It is found that the ellipticity determined from uniaxial and hydrostatic compressions varies with the equivalent plastic strain. © 2019 Trans Tech Publications Ltd, Switzerland.

关键词： Finite element method

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Distinct Topological Surface States on the Two Terminations of MnBi4Te7

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Physical Review X 2020年第3期10卷 031013-031013页

作者： Xuefeng Wu Jiayu Li Xiao-Ming Ma Yu Zhang Yuntian Liu Chun-Sheng Zhou Jifeng Shao Qiaoming Wang Yu-Jie Hao Yue Feng Eike F. Schwier Shiv Kumar Hongyi Sun Pengfei Liu Kenya Shimada Koji Miyamoto Taichi Okuda Kedong Wang Maohai Xie Chaoyu Chen Qihang Liu Chang Liu Yue Zhao Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology Shenzhen 518055 China Department of Physics The University of Hong Kong Hong Kong China Hiroshima Synchrotron Radiation Center Hiroshima University 2-313 Kagamiyama Higashi-Hiroshima 739-0046 Japan Guangdong Provincial Key Laboratory for Computational Science and Material Design Southern University of Science and Technology Shenzhen 518055 China

The recently discovered intrinsic magnetic topological insulator MnBi2Te4 has been met with unusual success in hosting emergent phenomena such as the quantum anomalous Hall effect and the axion insulator states. However, the surface-bulk correspondence of the Mn-Bi-Te family, composed by the superlatticelike MnBi2Te4/(Bi2Te3)n (n=0,1,2,3…) layered structure, remains intriguing but elusive. Here, by using scanning tunneling microscopy and angle-resolved photoemission spectroscopy techniques, we unambiguously assign the two distinct surface states of MnBi4Te7 (n=1) to the quintuple-layer (QL) Bi2Te3 termination and the septuple-layer (SL) MnBi2Te4 termination, respectively. A comparison of the experimental observations with theoretical calculations reveals diverging topological behaviors, especially the hybridization effect between the QL and SL, on the two terminations. We identify a gap on the QL termination, originating from the hybridization between the topological surface states of the QL and the bands of the SL beneath, and a gapless Dirac-cone band structure on the SL termination with time-reversal symmetry. The quasiparticle interference patterns further confirm the topological nature of the surface states for both terminations, continuing far above the Fermi energy. The QL termination carries a spin-helical Dirac state with hexagonal warping, while at the SL termination, a strongly canted helical state from the surface lies between a pair of Rashba-like splitting bands from its neighboring layer. Our work elucidates an unprecedented hybridization effect between the building blocks of the topological surface states and also reveals the termination-dependent time-reversal symmetry breaking in a magnetic topological insulator.

关键词： Dirac fermions Electronic structure Surface states Topological insulators Heterostructures Magnetic multilayers Topological materials Angle-resolved photoemission spectroscopy Density functional theory Scanning tunneling microscopy Scanning tunneling spectroscopy k dot p method

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Compound nonlinear energy sink with multiple motion types for absorbing energy from wide excitation ranges

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Journal of Sound and Vibration 2025年

作者： Jianen Chen Jiaqi Zhao Wei Zhang Min Sun Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin 300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin 300384 China School of Civil Engineering and Architecture Guangxi University Nanning 530004 China School of Science Tianjin Chengjian University Tianjin 300384 China

Nonlinear energy sink (NES) has garnered significant attention since its inception due to its notable broadband vibration reduction capability. However, the introduction of strong nonlinear characteristics by NESs complicates system responses, leading to a loss of effectiveness when the excitation force exceeds a specific threshold. Consequently, NESs have limited applicability in engineering because they are effective only within a constrained range of excitation amplitude. In this study, a compound NES (CNES) with multiple motion types is designed to extend the effective force range while maintaining broadband vibration reduction capability. The CNES is distinguished by its piecewise stiffness, collision mechanisms, and unique design of two-degree-of-freedom oscillators. The wide effective range of the CNES is demonstrated through slow linear sweep and fixed-frequency tests. The results indicate that the CNES effectively reduces vibrations in the primary oscillator (PO) with various resonant frequencies. Notably, the CNES achieves significant vibration reduction over a particularly wide range of excitation amplitude when controlling the PO with relatively high resonance frequencies (approximately 10.5 Hz and 19 Hz). However, a nonnegligible limitation of the CNES is its restricted effective range of excitation amplitude when the PO resonates at lower frequency (approximately 7 Hz). Moreover, five motion types of the CNES are identified and analyzed, with one motion type autonomously emerging in response to changes in excitation parameters, ensuring excellent vibration reduction performance across a wide excitation range. Finally, the performance of the CNES and a degraded single-degree-of-freedom CNES are compared to further demonstrate the extension effect of the multiple motion types on the effective range. The CNES can be used in scenarios where the parameters of protected systems and excitations vary widely, providing a thought to improve the NESs.

关键词： Compound nonlinearity compound features vibration reduction vibration test multiple motion types effective range

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RUArt: A novel text-centered solution for text-based visual question answering

arXiv

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arXiv 2020年

作者： Jin, Zan-Xia Wu, Heran Yang, Chun Zhou, Fang Qin, Jingyan Xiao, Lei Yin, Xu-Cheng Department of Computer Science and Technology School of Computer and Communication Engineering University of Science and Technology Beijing Beijing100083 China Department of Industrial Design School of Mechanical Engineering University of Science and Technology Beijing Beijing100083 China Company Limited Shenzhen518057 China Institute of Artificial Intelligence University of Science and Technology Beijing Beijing100083 China USTB-EEasyTech Joint Laboratory of Artificial Intelligence University of Science and Technology Beijing Beijing100083 China

Text-based visual question answering (VQA) requires to read and understand text in an image to correctly answer a given question. However, most current methods simply add optical character recognition (OCR) tokens extracted from the image into the VQA model without considering contextual information of OCR tokens and mining the relationships between OCR tokens and scene objects. In this paper, we propose a novel text-centered method called RUArt (Reading, Understanding and Answering the Related Text) for text-based VQA. Taking an image and a question as input, RUArt first reads the image and obtains text and scene objects. Then, it understands the question, OCRed text and objects in the context of the scene, and further mines the relationships among them. Finally, it answers the related text for the given question through text semantic matching and reasoning. We evaluate our RUArt on two text-based VQA benchmarks (ST-VQA and TextVQA) and conduct extensive ablation studies for exploring the reasons behind RUArt’s effectiveness. Experimental results demonstrate that our method can effectively explore the contextual information of the text and mine the stable relationships between the text and objects. Copyright © 2020, The Authors. All rights reserved.

关键词： Natural language processing systems

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Self-biased magnetoelectric switching at room temperature in three-phase ferroelectric-antiferromagnetic-ferrimagnetic nanocomposites (vol 4, pg 333, 2021)

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NATURE ELECTRONICS 2021年第6期4卷 448-448页

作者： Wu, Rui Zhang, Di Maity, Tuhin Lu, Ping Yang, Jie Gao, Xingyao Zhao, Shishun Wei, Xiucheng Zeng, Hao Kursumovic, Ahmed Tian, Guang Li, Weiwei Yun, Chao Wang, Yongqiang Ren, Zengyao Zhou, Ziyao Liu, Ming Zhang, Kelvin H. L. Jia, Quanxi Yang, Jinbo Wang, Haiyan MacManus-Driscoll, Judith L. Department of Materials Science & Metallurgy University of Cambridge Cambridge UK Materials Engineering Purdue University West Lafayette IN USA Sandia National Laboratories Albuquerque NM USA State Key Laboratory for Artificial Microstructure and Mesoscopic Physics School of Physics Peking University Beijing People’s Republic of China Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education & International Center for Dielectric Research Xi’an Jiaotong University Xi’an People’s Republic of China Department of Physics University at Buffalo—the State University of New York Buffalo NY USA Materials Science and Technology Division Los Alamos National Laboratory Los Alamos NM USA School of Materials Science and Engineering University of Science and Technology Beijing Beijing People’s Republic of China State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical Engineering Xiamen University Xiamen People’s Republic of China Department of Materials Design and Innovation University at Buffalo—the State University of New York Buffalo NY USA

Magnetoelectric systems could be used to develop magnetoelectric random access memory and microsensor devices. One promising system is the two-phase 3-1-type multiferroic nanocomposite in which a one-dimensional magnetic column is embedded in a three-dimensional ferroelectric matrix. However, it suffers from a number of limitations including unwanted leakage currents and the need for biasing with a magnetic field. Here we show that the addition of an antiferromagnet to a 3-1-type multiferroic nanocomposite can lead to a large, self-biased magnetoelectric effect at room temperature. Our three-phase system is composed of a ferroelectric Na0.5Bi0.5TiO3matrix in which ferrimagnetic NiFe2O4nanocolumns coated with antiferromagnetic p-type NiO are embedded. This system, which is self-assembled, exhibits a magnetoelectric coefficient of up to 1.38 × 10–9s m–1, which is large enough to switch the magnetic anisotropy from the easy axis (Keff= 0.91 × 104J m–3) to the easy plane (Keff= –1.65 × 104J m–3).

关键词： Nanocomposites

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Deformation characteristics and safety assessment of a high-speed railway induced by undercutting metro tunnel excavation

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第1期11卷 88-98页

作者： Wangping Qian Taiyue Qi Yunjian Zhao Yizhou Le Haiyang Yi Key Laboratory of Transportation Tunnel Engineering Ministry of Education Southwest Jiaotong University School of Civil Engineering Southwest Jiao tong University China Railway Design Corporation China Changjiang Construction Investment Corp.Ltd. North China Institute of Science and Technology

Stratum deformation(settlement) is a challenging issue in tunnel engineering, especially when construction of metro tunnels has to undercut high-speed railway. For this purpose, we used the FLAC30 software to analyze the stratum settlement characteristics of high-speed railway at different crossing angles intersected by metro tunnel, in terms of ground settlement trough, stratum slip line and irregularity of ballastless tracks. According to the evolution of the stratum settlement at different angle regions, an optimized angle is proposed for the actual project design. In order to reduce the influence of stratum settlement on the safety of high-speed railway, an approach of safety assessment is proposed for the shield engineering undercutting high-speed railway, as per Chinese specifications using numerical results and on-site conditions. A case study is conducted for the shield tunnel section crossing the Wuhan-Guangzhou High-speed Railway between the Guangzhou North Railway Station and the Huacheng Road Station, which represents the first metro tunnel project passing below a high-speed railway in China. A series of measures is taken to ensure the safe excavation of the shield tunnel and the operation of the high-speed railway. The results can provide a technical support for performing a safety evaluation between high-speed railways and metro tunnels.

关键词： Metro tunnel excavation High-speed railway Settlement characteristics Safety assessment Numerical simulation Case application

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Accelerated removal of polycyclic aromatic hydrocarbon by amorphous boron- or citric acid- co -Fe(III) activated sodium percarbonate process: In aqueous solution and soil slurry

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Journal of Water Process Engineering 2025年 75卷

作者： Xianxian Sheng Tianliang Wang Guilu Zeng Xiang Zhang Mudassir Habib Shuguang Lyu State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process East China University of Science and Technology Shanghai 200237 China China Construction Sixth Engineering Bureau Hydropower Construction Co. Ltd Tianjin 300222 China Zhejiang Key Laboratory of Environmental Protect Technology Eco-Environmental Sciences Research & Design Institute of Zhejiang Province Hangzhou 310007 China Shanghai Municipal Engineering Design Institute (Group) Co. Ltd. North Zhongshan 2nd Road Shanghai 200092 China

In the advanced oxidation process (AOPs) induced by sodium percarbonate (SPC), reactive oxygen species (ROS) can be scavenged by a large amount of dissolved Fe(II) released within a short time. To address this issue, a slow-release Fe(II) process is proposed in this study, thereby enhancing the degradation of contaminants. SPC/Fe(III)/amorphous boron (B) and SPC/Fe(III)/citric acid (CA) procedures were employed to remove polycyclic aromatic hydrocarbons (PAHs), with B as the reductant and CA as the chelator. Fluoranthene (FLT) removal in SPC/Fe(III)/B process contributed to HO•, while HO• and O 2 − • were responsible for FLT degradation via SPC/Fe(III)/CA system. SPC/Fe(III)/CA system exhibits more adaptability to intricate water quality circumstances compared to SPC/Fe(III)/B system. The bio-toxicity of FLT and their degradation intermediates was evaluated via the Toxicity Estimation Software Tool (T.E.S.T.), revealing a reduction in oral rat LD50, developmental toxicity, mutagenicity, and bioconcentration factor of the degradation intermediates relative to FLT. Both amorphous B- or CA-assisted SPC/Fe(III) processes were shown to be eco-friendly through luminosity inhibition tests with Vibrio fischeri . Experiments on soil slurry revealed that SPC/Fe(III)/CA system was feasible for the removal of complex PAHs, directing the SPC-induced AOPs process for the remediation of PAHs contaminated soils and groundwater.

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Symmetry-Protected Topological Triangular Weyl Complex

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Physical Review Letters 2020年第10期124卷 105303-105303页

作者： R. Wang B. W. Xia Z. J. Chen B. B. Zheng Y. J. Zhao H. Xu Department of Physics & Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen 518055 People’s Republic of China Institute for Structure and Function & Department of Physics & Center for Quantum Materials and Devices Chongqing University Chongqing 400044 People’s Republic of China Department of Physics South China University of Technology Guangzhou 510640 People’s Republic of China Guangdong Provincial Key Laboratory of Computational Science and Material Design Southern University of Science and Technology Shenzhen 518055 People’s Republic of China

Weyl points are often believed to appear in pairs with opposite chirality. In this work, we show by first-principles calculations and symmetry analysis that single Weyl phonons with linear dispersion and double Weyl phonons with quadratic dispersion are simultaneously present between two specific phonon branches in realistic materials with trigonal or hexagonal lattices. These phonon Weyl points are guaranteed to locate at high-symmetry points due to the screw rotational symmetry, forming a unique triangular Weyl complex. In sharp contrast to conventional Weyl systems with surface arcs terminated at the projections of a pair of Weyl points with opposite chirality, the phonon surface arcs of the unconventional triangular Weyl complex connect the projections of one double Weyl point and two single Weyl points. Importantly, the phonon surface arcs originating from the triangular Weyl complex are extremely long and span the entire surface Brillouin zone. Furthermore, there are only nontrivial phonon surface states across the isofrequency surface, which facilitates their detection in experiments and further applications. Our work not only offers the promising triangular phonon Weyl complex but also provides guidance for exploring triangular Weyl bosons in both phononic and photonic systems.

关键词： Phonons Symmetry protected topological states Topological materials Weyl semimetal

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Numerical modeling of anisotropy paradoxes in direct current resistivity and time-domain induced polarization methods

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Applied Geophysics 2021年第1期18卷 117-127,130页

作者： Song Tao Liu Yun Wang Yun and Li Bin College of Mathematics and Information Science Guiyang UniversityGuiyang 550005China State Key Laboratory of Ore Deposit Geochemistry Institute of Geochemistry Chinese Academy of SciencesGui Yang 550081China College of Earth Sciences Yunnan UniversityKunming650500China School of Geophysics and Information Technology China University of GeoscienceBeijing100083China Sichuan Highway Planning SurveyDesign And Research Institute LtdChengdu 610041China.

Based on an analytical solution for the current point source in an anisotropic half-space,we study the apparent resistivity and apparent chargeability of a transversely isotropic medium with vertical and horizontal axes symmetry,*** then provide a simple derivation of the anisotropy paradoxes in direct current resistivity and time-domain induced polarization *** to the mean resistivity,we propose a formulation for deriving the mean *** also present a three-dimensional finite element algorithm for modeling the direct current resistivity and time-domain induced polarization using an unstructured tetrahedral ***,we provide the apparent resistivity and apparent chargeability curves of a tilted,transversely isotropic medium with diff erent angles,*** subsequent results illustrate the anisotropy paradoxes of direct current resistivity and time-domain induced polarization.

关键词： Paradox of anisotropy direct current resistivity time-domain induced polarization FEM

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Electronic correlations and absence of superconductivity in the collapsed phase of LaFe2As2

arXiv

引用

arXiv 2020年

作者： Zhao, Jianzhou Wang, Yilin Feng, Xiaolong Yang, Shengyuan A. Co-Innovation Center for New Energetic Materials Southwest University of Science and Technology Mianyang621010 China Research Laboratory for Quantum Materials Singapore University of Technology and Design Singapore487372 Singapore Hefei National Laboratory for Physical Sciences at Microscale University of Science and Technology of China HefeiAnhui230026 China Center for Quantum Transport and Thermal Energy Science School of Physics and Technology Nanjing Normal University Nanjing210023 China

The interplay between structural phase and electronic correlations has been an intriguing topic of research. An prominent example is the pressure-induced uncollapsed to collapsed tetragonal phase transition observed in CaFe2As2, which is accompanied with the emergence of superconductivity in the collapsed phase. Recently, a very similar structural phase transition was discovered in LaFe2As2, but in contrast to CaFe2As2, superconductivity was only observed in the uncollapsed phase, not the collapsed phase. Previous studies have attributed this puzzling observation to the differences in the two materials' band coherence, orbital occupation, and Fermi surface topology. Here, we present a comparative study of LaFe2As2 and CaFe2As2 using the DFT+DMFT method. Surprisingly, we find that although La appears to have a valence higher than Ca, the doped one electron actually primarily resides on the La site. This leads to almost the same total Fe-3d occupancy and electronic correlation strength as well as similar Lifshiftz transition in the Fermi surface topology for the two materials. In addition, we show that the two materials in both structural phases belong to the category of Hund's metals. Our results indicate that the electronic structures of LaFe2As2 and CaFe2As2 are not too different, which further suggest that superconductivity might also be induced in the collapsed phase of LaFe2As2 under similar non-hydrostatic conditions as for CaFe2As2. © 2020, CC0.

关键词： Electronic structure

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