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Floquet规范转变诱导拓扑π模产生的理论分析
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作者 宋万鸽 祝世宁 李涛 《人工晶体学报》 CAS 北大核心 2021年第7期1340-1347,1355,共9页
拓扑绝缘体是一类内部绝缘而在表面可以导电的物态,其倒空间的能带具有非平庸的拓扑特性,而在其实空间的边界上具有可以单向传播的边界态。这种拓扑界面态出现往往依赖于界面处的拓扑相变。而最近有研究在一类Floquet的拓扑体系中实验... 拓扑绝缘体是一类内部绝缘而在表面可以导电的物态,其倒空间的能带具有非平庸的拓扑特性,而在其实空间的边界上具有可以单向传播的边界态。这种拓扑界面态出现往往依赖于界面处的拓扑相变。而最近有研究在一类Floquet的拓扑体系中实验观测到一种规范场相变诱导产生的拓扑π模,这种拓扑态的产生可能不依赖于拓扑相变。本文对于这种规范场诱导的拓扑π模的产生机理做出了理论解释。两个Floquet规范相反的体系的哈密顿量由于规范相变而具有相反的π能隙质量项,类似于Jackiw-Rebbi模型,从而导致拓扑界面态的出现。本文的研究为规范场相变诱导拓扑模式的产生提供了理论基础,并加深了人们对于Floquet规范场的理解。 展开更多
关键词 floquet系统 拓扑π模 人工规范场 Su-Schriffer-Heeger模型 Jackiw-Rebbi模型 拓扑绝缘体
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Stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling 被引量:2
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作者 孔令飞 李言 +3 位作者 吕延军 李德信 李淑娟 汤奥斐 《Journal of Central South University》 SCIE EI CAS 2009年第3期451-457,共7页
The stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling were analyzed. The effects of the fluctuation of the cutting force, the mass eccentricity and the hydrodynamic f... The stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling were analyzed. The effects of the fluctuation of the cutting force, the mass eccentricity and the hydrodynamic forces of cutting fluid could be taken into consideration in the model of drilling shaft system. Based on the isoparametric finite element method, the variational form of Reynolds equation in hydrodynamic fluid was used to calculate nonlinear hydrodynamic forces and their Jacobian matrices simultaneously. In the stability analysis, a new shooting method for rapidly determining the periodic orbit of the nonlinear drilling shaft system and its period was presented by rebuilding the traditional shooting method and changing the time scale. Through the combination of theories with experiment, the correctness and effectiveness of the above methods are verified by using the Floquet theory. The results show that the mass eccentricity can inhibit the whirling motion of drilling shaft to some extent. 展开更多
关键词 copper stave deep hole drilling drilling shaft NONLINEARITY BIFURCATION
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