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We consider a symbolic coding of bi-infinite non periodic geodesics on the L-shaped translation surface tiled by three squares. Each bi-infinite non periodic geodesic is associated with a cutting sequence corresponding to the sequence of labeled saddle connections hit. We prove that there is a relationship between the cutting sequences and the actions of some affine automorphisms of the translation surface. We also get an explicit formula to determine the direction of a bi-infinite non periodic geodesic by using the corresponding cutting sequence. 相似文献
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By transforming a 3D problem into some related 2D problems, the dimension splitting element-free Galerkin(DSEFG) method is proposed to solve 3D transient heat conduction problems. The improved element-free Galerkin(IEFG) method is used for 2D transient heat conduction problems, and the finite difference method is applied in the splitting direction. The discretized system equation is obtained based on the Galerkin weak form of 2D problem; the essential boundary conditions are imposed with the penalty method; and the finite difference method is employed in the time domain. Four exemplary problems are chosen to verify the efficiency of the DSEFG method. The numerical solutions show that the efficiency and precision of the DSEFG method are greater than ones of the IEFG method for 3D problems. 相似文献
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准连续体方法是一种将连续介质方法和原子模拟相耦合的多尺度模拟方法。该方法巧妙地将分子静力学与有限元法相结合,在变形梯度较小的规则区域采用代表性原子作为计算点,以此为节点形成有限元网格,其周围其他原子的位置通过插值得到。代表性原子的引入,使系统原子势能的计算大大简化。自适应手段的应用,保证了材料缺陷核心附近原子尺度的细节描述。与其他纳米力学计算方法相比,准连续体方法具有计算精度高,计算规模大等优点。本文主要介绍了准连续体方法的基本原理及发展状况,归纳并总结了这一些优点及今后的发展方向。 相似文献
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We study the relevance of nucleon pairs with higher spins, in addition to spin-zero and spin-two pairs (i.e., SD pairs), in low-lying states of even-even Xe nuclei. By including those higher-spin pairs in our configuration, we recalculate energy level schemes, electrical quadrupole moments, magnetic moments and electric quadrupole transition rates, for low-lying states of even-even 128–142Xe nuclei. The agreement between our calculated results and the experimental data is substantially improved in comparison with previous studies. 相似文献
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We study the relevance of nucleon pairs with higher spins, in addition to spin-zero and spin-two pairs (i.e., S D pairs), in low-lying states of even-even Xe nuclei. By including those higher-spin pairs in our configuration, we recalculate energy level schemes, elec trical quadrupole moments, magnetic moments and electric quadrupole transition rates, for low-lying states of even-even 128-142Xe nuclei. The agreement between our calculated results and the experimental data is substantially improved in compari... 相似文献
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Ca3Al2Ge3O12:Cr3+的光谱性质及晶场参数计算 总被引:1,自引:0,他引:1
为了解Cr3+离子在钙铝锗酸盐Ca3Al2Ge3O12:石榴石中的光谱性质, 合成了Ca3Al2Ge3O12:Cr3+多晶材料;测量了其X射线衍射图, 漫反射光谱, 激发、发射光谱等;分析了Cr3+离子在钙铝锗酸盐中的发光特性;计算了其晶场强度(Dq/B), Stokes位移(ΔEs)及黄昆-里斯因子(S)等. 在450 nm激发下, Ca3Al2Ge3O12:Cr3+室温发射光谱主要由三个宽带及附加其上的弱R线构成, 分别对应于Cr3+离子的4T1、 4T2、2T2到 4A2 能级跃迁. 低温时R线变得强而锐. 通过计算, Dq/B=2.43, ΔEs=1884 cm-1, S=5.21. 表明在Ca3Al2Ge3O12中Cr3+离子处于较弱的晶场强度, 电子-声子耦合较强, 为发展可调谐激光材料提供重要线索. 相似文献
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REN HongPing CHENG YuMin & ZHANG Wu School of Computer Engineering Science Shanghai University Shanghai China 《中国科学:物理学 力学 天文学(英文版)》2010,(4)
The paper begins by discussing the interpolating moving least-squares (IMLS) method. Then the formulae of the IMLS method obtained by Lancaster are revised. On the basis of the boundary element-free method (BEFM), combining the boundary integral equation method with the IMLS method improved in this paper, the interpolating boundary element-free method (IBEFM) for two-dimensional elasticity problems is presented, and the corresponding formulae of the IBEFM for two-dimensional elasticity problems are obtained. In the IMLS method in this paper, the shape function satisfies the property of Kronecker δ function, and then in the IBEFM the boundary conditions can be applied directly and easily. The IBEFM is a direct meshless boundary integral equation method in which the basic unknown quantity is the real solution to the nodal variables. Thus it gives a greater computational precision. Numerical examples are presented to demonstrate the method. 相似文献
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