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151.
留数定理是高校物理专业必修课程数学物理方法中的一个重要定理.传统教学中关于该定理的讲授着重于数学公式的推导和数学思想的传达,而对于其在具体物理问题上的应用鲜有涉及.本文以一维Su-Schrieffer-Heeger模型的拓扑相变问题为例,阐明了如何利用留数定理解析得到二阶位移量的表达式并用该物理量表征拓扑相变.在讲授留数定理的教学过程中引入具体物理问题的分析实例,可以使学生更深刻地理解数学定理中的物理内涵. 相似文献
152.
The proposal of higher-order topology leads to intriguing wave propagation properties beyond the conventional bulk-boundary principle in condensed matter physics. Theoretical and experimental models have been conducted to reveal exotic higher-order hinge and corner states in lower dimensions. Meanwhile, this concept is extended to semimetals and verified in platforms like acoustic and photonic systems. However, most existing schemes are confined to Cn-symmetric-like frameworks. Here a phononic higher-order Weyl semimetal (HOWSM) is put forward by introductions of artificial gauge flux shape. Distinguished from most existing schemes, the traditional two-dimensional lattice with a vertical screw-extending operation is deformed, which guarantees the emergence of higher-order Weyl points. The invariant index is utilized to measure different phases between non-trivial topological and normal insulators visibly. Simulation results indicate that the structure supports robust hinge wave transmission in a piling sample. This work brings new approaches for constructing HOWSMs and enriches the potential applications in manufacturing high-performance acoustic devices. 相似文献
153.
Dong-Yang Jing 《中国物理 B》2023,32(1):17401-017401
One-dimensional s-wave superconductor with spin-orbit coupling is a platform for the realization of Majorana zero modes. The spin-exchange with the magnetic skyrmion lattice can induce spin-orbit coupling in a s-wave superconductor system and the effects are different from the constant spin-orbit coupling. The strength of the effective spin-orbit coupling as well as the rich topoloigcal phase diagram are directly connected to the radius of the skyrmion lattice R. We obtain the rich topological phase diagram of this system with different skyrmion lattice radii by numerically evaluating the spectrum of the system under the periodic boundary condition, and we also find the Majorana zero modes under the open boundary condition to verify the bulk-edge correspondence. 相似文献
154.
Evolution of polarization singularities accompanied by avoided crossing in plasmonic system 下载免费PDF全文
Yi-Xiao Peng 《中国物理 B》2023,32(1):14201-014201
The evolution of polarization singularities supported in a one-dimensional periodic plasmonic system is studied. The lateral inversion symmetry of the system, which breaks the in-plane inversion symmetry and up-down mirror symmetry simultaneously, yields abundant polarization states. A complete evolution process with geometry for the polarization states is traced. In the evolution, circularly polarized points (C points) can stem from 3 different processes. In addition to the previously reported processes occurring in an isolated band, a new type of C point appearing in two bands simultaneously due to the avoided band crossing, is observed. Unlike the dielectric system with a similar structure which only supports at-$\varGamma$ bound states in the continuum (BICs), accidental BICs off the $\varGamma$ point are realized in this plasmonic system. This work provides a new scheme of polarization manipulation for the plasmonic systems. 相似文献
155.
Xu-Tao Zeng Ziyu Chen Cong Chen Bin-Bin Liu Xian-Lei Sheng Shengyuan A. Yang 《Frontiers of Physics》2023,18(1):13308
Dirac semimetals (DSMs) are an important class of topological states of matter. Here, focusing on DSMs of band inversion type, we investigate their boundary modes from the effective model perspective. We show that in order to properly capture the boundary modes, k-cubic terms must be included in the effective model, which would drive an evolution of surface degeneracy manifold from a nodal line to a nodal point. Sizable k-cubic terms are also needed for better exposing the topological hinge modes in the spectrum. Using first-principles calculations, we demonstrate that this feature and the topological hinge modes can be clearly exhibited in β-CuI. We extend the discussion to magnetic DSMs and show that the time-reversal symmetry breaking can gap out the surface bands and hence is beneficial for the experimental detection of hinge modes. Furthermore, we show that magnetic DSMs serve as a parent state for realizing multiple other higher-order topological phases, including higher-order Weyl-point/nodal-line semimetals and higher-order topological insulators. 相似文献
156.
J. M. Soriano 《应用数学和力学(英文版)》2006,27(9):1265-1274
Sufficient conditions were given to assert that between any two Banach spaces over K, Fredholm mappings share at least one value in a specific open ball. The proof of the result is constructive and based upon continuation methods. 相似文献
157.
The topological optimization for truss structures with stress constraints based on the exist-null combined model 总被引:7,自引:0,他引:7
A new exist-null combined model is proposed for the structural topology optimization. The model is applied to the topology
optimization of the truss with stress constraints. Satisfactory computational result can be obtained with more rapid and more
stable convergence as compared with the cross-sectional optimization. This work also shows that the presence of independent
and continuous topological variable motivates the research of structural topology optimization.
The project supported by the State Key Laboratory for Structural Analysis of Industrial Equipment, Dalian University of Technology. 相似文献
158.
I.Introduction'In1969,KyFanl[Iprovedthefollowingwell-knownresultsonbestapproximation.Theorem1.1LetXbeanonemptycompactconvexsubsetofalocallyconvextopologicalvectorspaceEandf:X~Ebeacontinuousmapping.TheneitherfhasafixedpointinX,orthereexistapointyo6XandacontinuousseminormponEsucllthat0
相似文献
159.
平面膜结构拓扑优化的有无复合体方法 总被引:18,自引:3,他引:18
将作者对桁架在应力约束下结构拓扑优化的有无复合体模型发展到平面膜结构在应力、位移约束下结构拓扑优化的建模与求解。同时提出了该模型的有效解法,获得了令人满意的数值结果。本文工作表明独立连续拓扑变量的提出对于结构拓扑优化的研究是有意义的。 相似文献
160.
By means of ink trace visualization of the flows in conventional straight, positively curved and negatively curved cascades
with tip clearance, and measurement of the aerodynamic parameters in the transverse section, and by appling topology theory,
the structures on both endwalls and blade surfaces were analyzed. Compared with conventional straight cascade, blade positive
curving eliminates the separation line of the upper passage vortex and leads the secondary vortex to change from close separation
to open separation, while blade negative curving effects merely the positions of singular points and the intensities and scales
of vortex.
Foundation items: 973 Project of China; the Doctoral Foundation of Education Ministry of China (EDAF24403003)
Biography: YANG Qing-hai (1969−) 相似文献