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From Topological Nodal-Line Semimetals to Quantum Spin Hall Insulators in Tetragonal SnX Monolayers(X=F,Cl,Br,I)

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Chinese Physics Letters 2024年第6期41卷 98-111页

作者：朱晔赵宝薛阳徐玮徐文婷杨中芹 State Key Laboratory of Surface Physics Key Laboratory of Computational Physical Sciences(MOE)and Department of PhysicsFudan UniversityShanghai 200433China Shandong Key Laboratory of Optical Communication Science and Technology School of Physics Science and Information TechnologyLiaocheng UniversityLiaocheng 252059China School of Physics East China University of Science and TechnologyShanghai 200237China Shanghai Qi Zhi Institute Shanghai 200030China

Two-dimensional(2D)topological materials have recently garnered significant interest due to their profound physical properties and promising applications for future quantum *** various topological states within one type of materials is,however,seldom *** on first-principles calculations and tightbinding models,we investigate topological electronic states in a novel family of 2D halogenated tetragonal stanene(T-SnX,X=F,Cl,Br,I).All the four monolayers are found to be unusual topological nodal-line semimetals(NLSs),protected by a glide mirror *** spin-orbit coupling(SOC)is turned on,T-SnF and TSnCl are still ascertained as topological NLSs due to the remaining band inversion,primarily composed of Sn pxy orbitals,while T-Sn Br and T-SnI become quantum spin Hall *** phase transition is ascribed to moving up in energy of Sn s orbitals and increasing of SOC *** topology origin in the materials is uniformly rationalized through elementary band *** robust and diverse topological states found in the 2D T-SnX monolayers position them as an excellent material platform for development of innovative topological electronics.

关键词： topological metals quantum

A NONLOCAL KRONECKER-BASIS-REPRESENTATION METHOD FOR LOW-DOSE CT SINOGRAM RECOVERY

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Journal of computational Mathematics 2024年第4期42卷 1080-1108页

作者： Jian Lu Huaxuan Hu Yuru Zou Zhaosong Lu Xiaoxia Liu Keke Zu Lin Li Shenzhen Key Laboratory of Advanced Machine Learning and applications College of Mathematics and StatisticsShenzhen UniversityShenzhen 518060China National Center for Applied Mathematics Shenzhen(NCAMS) Shenzhen 518055China Department of Industrial and Systems Engineering University of Minnesota Twin CitiesMinneapolisMN55455USA Department of Applied Mathematics The Hong Kong Polytechnic UniversityHong Kong SARChina School of Electronic Engineering Xidian UniversityXi'an 710071China

Low-dose computed tomography(LDCT)contains the mixed noise of Poisson and Gaus-sian,which makes the image reconstruction a challenging *** order to describe the statistical characteristics of the mixed noise,we adopt the sinogram preprocessing as a stan-dard maximum a posteriori(MAP).Based on the fact that the sinogram of LDCT has non-local self-similarity property,it exhibits low-rank *** conventional way of solving the low-rank problem is implemented in matrix forms,and ignores the correlations among similar patch *** avoid this issue,we make use of a nonlocal Kronecker-Basis-Representation(KBR)method to depict the low-rank problem.A new denoising model,which consists of the sinogram preprocessing for data fidelity and the nonlocal KBR term,is developed in this *** proposed denoising model can better illustrate the generative mechanism of the mixed noise and the prior knowledge of the ***-merical results show that the proposed denoising model outperforms the state-of-the-art algorithms in terms of peak-signal-to-noise ratio(PSNR),feature similarity(FSIM),and normalized mean square error(NMSE).

关键词： Low-dose computed tomography Kronecker-basis-representation Low-rank imation.Noise-generating-mechanism

Improving optomechanical gyroscopes by coherent quantum noise cancellation processing

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Science China(Physics,Mechanics & Astronomy) 2018年第9期61卷 19-25页

作者： Kai Li Sankar Davuluri Yong Li Beijing computational Science Research Center Beijing 100193 China Synergetic Innovation Center for Quantum Effects and applications Hunan Normal University Changsha 410081 China

Coherent quantum noise cancellation(CQNC) method is used to beat standard quantum limit(SQL) for improving the performance of quantum optomechanical gyroscopes. The protocol for realizing CQNC is achieved by constructing an effective negative mass mechanical oscillator, which is simulated by an ancillary cavity. This oscillator shows an antiresponse relative to that of a real mechanical oscillator. Thus, the optomechanical back-action noise is counteracted or restrained, and we could increase our signal by increasing the coupling strength without increasing the noise.

关键词： CQNC optomechanics gyroscope

CONVERGENCE OF AN EXPLICIT UPWIND FINITE ELEMENT METHOD TO MULTI-DIMENSIONAL CONSERVATION LAWS

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Journal of computational Mathematics 2001年第1期19卷 87-100页

作者： Jin-chao Xu Lung-an Ying Center for computational Mathematics and applications and Department of Mathematics Pennsylvania State UniversityU.S.A School of Mathematical Sciences Peking UniversityBeijing 100871China

Investigates the convergence of an explicit upwind finite element method, the edge-averaged finite element method to multidimensional scalar conservation laws. Discussion on the finite element scheme and main converge... 详细信息

关键词： conservation law finite element method convergence

A comparison of two formulations of the fin efficiency for straight fins

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Acta Mechanica Sinica 2012年第2期28卷 444-449页

A formulation of the fin efficiency based on New- ton＇s law of cooling is compared with a formulation based on a ratio of heat transferred from the fin surface to the sur- rounding fluid to the heat conducted through the base. The first formulation requires that the solution of the nonlinear fin equations for constant heat transfer coefficient and constant thermal conductivity is known, whilst the second formulation of the fin efficiency requires only that a first integral of the model equation is known. This paper shows the first for- mulation of the fin efficiency contains approximation errors as only power series and approximate solutions to the non- linear fin equations have been determined. The second for- mulation of the fin efficiency is exact when the first integrals can be determined.

关键词： Fin equation First integral Fin efficiency

THE ACCELERATED SEARCH-EXTENSION METHOD FOR COMPUTING MULTIPLE SOLUTIONS OF SEMILINEAR PDEs

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Acta Mathematica Scientia 2009年第4期29卷 803-816页

作者：刘跃武谢资清陈传淼 Key Laboratory of computational and Stochastic Mathematics and Its applications Universities of Hunan Province Hunan Normal University College of Science Hunan Agricultural University

In this paper, we propose an accelerated search-extension method （ASEM） based on the interpolated coefficient finite element method, the search-extension method （SEM） and the two-grid method to obtain the multiple solutions for semilinear elliptic equations. This strategy is not only successfully implemented to obtain multiple solutions for a class of semilinear elliptic boundary value problems, but also reduces the expensive computation greatly. The numerical results in I-D and 2-D cases will show the efficiency of our approach.

关键词： semilinear PDEs multiple solutions accelerated search-extension method (ASEM) two-grid method

Quasi-two-dimensional strong liquid-like dynamics of surface atoms in metallic glasses

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Science China(Physics,Mechanics & Astronomy) 2024年第3期67卷 102-109页

作者： Bing Wang Xuanqiao Gao Rui Su Pengfei Guan School of Physical Science and Technology Northwestern Polytechnical UniversityXi'an 710072China Innovation Center NPU Chongqing Northwestern Polytechnical UniversityChongqing 401135China School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi'an 710072China Northwest Institute for Nonferrous Metal Research Xi'an 710016China Institute of Advanced Magnetic Materials College of Materials and Environmental EngineeringHangzhou Dianzi University Hangzhou 310018China Beijing computational Science Research Center Beijing 100093China

The fast dynamic properties of the surface of metallic glasses(MGs) play a critical role in determining their potential applications. However, due to the significant difference in thermal history between atomic simulation models and laboratory-made samples, the atomic-scale behaviors of the fast surface dynamics of MGs in experiments remain uncertain. Herein, we prepared model MG films with notable variations in thermal stability using a recently developed efficient annealing protocol, and investigated their atomic-scale dynamics systematically. We found that the dynamics of surface atoms remain invariant, whereas the difference in dynamical heterogeneity between surface and interior regions increases with the improvement of thermal stability. This can be associated with the more pronounced correlation between atomic activation energy spectra and depth from the surface in samples with higher thermal stability. In addition, dynamic anisotropy appears for surface atoms, and their transverse dynamics are faster than normal components, which can also be interpreted by activation energy spectra. Our results reveal the presence of strong liquid-like atomic dynamics confined to the surface of laboratory-made MGs, illuminating the underlying mechanisms for surface engineering design, such as cold joining by ultrasonic vibrations and superlattice growth.

关键词： metallic glasses thermal stability invariant surface dynamics potential energy landscape dynamic anisotropy and heterogeneity

Optimized generation of entanglement based on the f-STIRAP technique

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Communications in Theoretical Physics 2024年第7期76卷 37-43页

作者： Dongni Chen Jiahui Li Stefano Chesi Ying-Dan Wang Department of Physics Korea UniversitySeoul 02841South Korea School of Quantum Information Future Technology Henan UniversityZhengzhou 450046China Beijing computational Science Research Center Beijing 100193China Department of Physics Beijing Normal UniversityBeijing 100875China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China

We consider generating maximally entangled states(Bell states)between two qubits coupled to a common bosonic mode,based on *** the systematic approach developed by Wang et al(2017 New ***.19093016),we quantify the effects of non-adiabatic leakage and system dissipation on the entanglement generation,and optimize the entanglement by balancing non-adiabatic leakage and system *** find the analytical expressions of the optimal coupling profile,the operation time,and the maximal *** findings have broad applications in quantum state engineering,especially in solid-state devices where dissipative effects cannot be neglected.

关键词： f-STIRAP entanglement optimization perturbation theory

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Numerical Simulation of Dam-Break Flows Using Radial Basis Functions: Application to Urban Flood Inundation

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American Journal of computational Mathematics 2024年第3期14卷 318-332页

作者： Abdoulhafar Halassi Bacar Said Charriffaini Rawhoudine Laboratoire des Mathmatiques Statistiques Informatique et Applications (LMSIA) Dpartement des Mathmatiques Physique-Chimie et Informatique (MPCI) Facult des Sciences et Techniques Universit des Comores Moroni Comoros

Dam-break flows pose significant threats to urban areas due to their potential for causing rapid and extensive flooding. Traditional numerical methods for simulating these events struggle with complex urban landscapes. This paper presents an alternative approach using Radial Basis Functions to simulate dam-break flows and their impact on urban flood inundation. The proposed method adapts a new strategy based on Particle Swarm Optimization for variable shape parameter selection on meshfree formulation to enhance the numerical stability and convergence of the simulation. The method’s accuracy and efficiency are demonstrated through numerical experiments, including well-known partial and circular dam-break problems and an idealized city with a single building, highlighting its potential as a valuable tool for urban flood risk management.

关键词： Dam-Break Flows Numerical Simulation Shallow Water Equations Radial Basis Functions Urban Flood Inundation