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满足螺旋边界条件的额外维存在时的标量场Casimir效应(英文)
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作者 葛飞飞 翟向华 《上海师范大学学报(自然科学版)》 2012年第6期559-564,共6页
研究了满足螺旋边界条件的额外维存在时的平行板标量场Casimir效应.利用Zeta函数正则化方法,得到了用第二类变形Bessel函数表示的Casimir力.发现Casimir力总是吸引力,但是对于相同尺度的螺旋结构参数和平板间的距离,与不存在额外维的情... 研究了满足螺旋边界条件的额外维存在时的平行板标量场Casimir效应.利用Zeta函数正则化方法,得到了用第二类变形Bessel函数表示的Casimir力.发现Casimir力总是吸引力,但是对于相同尺度的螺旋结构参数和平板间的距离,与不存在额外维的情形相比,平板间Casimir力的大小降低了一个数量级.螺旋结构参数越小,Casimir力的大小降低越多. 展开更多
关键词 CASIMIR效应 螺旋边界条件 额外维度 Zeta函数正则化
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基于螺旋线上谱因式分解的地震波场隐式辛算法 被引量:28
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作者 罗明秋 刘洪 李幼铭 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2001年第3期379-388,共10页
均匀介质、复杂各向同性介质和各向异性介质中的地震波传播过程 ,可用统一形式的标量声波方程描述 .考虑到在无损耗条件下 ,地震波方程描述了地震波场这一个无穷维的哈密顿体系随时间的演化过程 ,该过程为一个单参数连续辛变换 ,因而可... 均匀介质、复杂各向同性介质和各向异性介质中的地震波传播过程 ,可用统一形式的标量声波方程描述 .考虑到在无损耗条件下 ,地震波方程描述了地震波场这一个无穷维的哈密顿体系随时间的演化过程 ,该过程为一个单参数连续辛变换 ,因而可以在其哈密顿形式表述下导出其辛格式 .与显式辛算法相比 ,隐式辛格式对应的隐式辛几何算法具有无条件稳定的特点 ,可以允许较大的计算步长 .但是由于隐式算法不可避免地面临高阶矩阵的求逆 ,其每一步的计算速度较慢 .为实现矩阵快速求逆 ,文中采用了螺旋边界条件下谱因式分解的方法 .在螺旋边界条件下 ,需要求逆的矩阵化为带状矩阵 ,而且其各列非零元素的位置和大小具有非常好的相似性 ,因而可以采用谱因式分解的方法实现快速LU分解 .文中采用二阶精度的隐式蛙跳辛格式和谱因式分解方法 ,计算了常速度、层状介质和Marmousi模型中的波场 .计算表明 。 展开更多
关键词 地震波场 螺旋边界条件 隐式辛算法 谱因式分解 标量波动方程 弹性波动方程
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适用于三维隐式叠前深度偏移中矩阵求逆的混合算法 被引量:7
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作者 罗明秋 朱国同 +1 位作者 刘洪 李幼铭 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2003年第5期684-689,共6页
在深度偏移方法中 ,把二维隐式方法推广到三维 ,就会面对一个分块对角矩阵求逆问题 .通常 ,这种矩阵的求逆将耗费大量计算时间 ,严重制约了三维隐式方法偏移在实际资料处理中的广泛应用 .在螺旋边界条件下 ,该矩阵H具有Toeplitz结构的... 在深度偏移方法中 ,把二维隐式方法推广到三维 ,就会面对一个分块对角矩阵求逆问题 .通常 ,这种矩阵的求逆将耗费大量计算时间 ,严重制约了三维隐式方法偏移在实际资料处理中的广泛应用 .在螺旋边界条件下 ,该矩阵H具有Toeplitz结构的正定厄密矩阵 ,其快速求逆可由谱法LU分解或直解法快速实现 .本文结合谱法LU分解和直接解法方法的优点 ,提出了一种混合算法 .文中采用谱分解方法建立起矩阵列元素的谱分解表 ,并采用直解法的递推公式 ,可以快速给出矩阵的分解 .通过与谱法分解和直解法在分解精度和分解速度两方面的比较表明 ,本文方法与谱法相比 ,在非均匀介质中亥姆霍兹算子矩阵分解时的精度提高 10倍 ;在计算速度方面 ,混合方法比简化后的直解法快 .因此 ,该方法的提出 ,在计算精度许可的条件下 ,最大限度地减少三维隐式差分偏移中矩阵求逆占用的时间 ,从而使得该方法能真正用于实际地震资料的处理 . 展开更多
关键词 叠前深度偏移 螺旋边界条件 阵求逆 混合算法 LU分解 谱因式分解
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Ising模型的Monte-Carlo模拟 被引量:1
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作者 吴国军 胡经国 《吉首大学学报》 2000年第2期74-76,共3页
在平面四角点阵上 ,以Ising模型为框架 ,在IBM -PC机上用Monte -Carlo方法模拟了螺旋边界、半自由边界及自由边界条件下铁磁系统的相图 。
关键词 ISING模型 相图 MONTE-CARLO方法 边界条件 铁磁Ising系统 螺旋边界 半自由边界
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单层二维量子自旋霍尔绝缘体1T'-WTe_(2)研究进展 被引量:1
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作者 贾亮广 刘猛 +2 位作者 陈瑶瑶 张钰 王业亮 《物理学报》 SCIE EI CAS CSCD 北大核心 2022年第12期297-310,共14页
量子自旋霍尔效应通常存在于二维拓扑绝缘体中,其具有受拓扑保护的无耗散螺旋边界态.2014年,理论预言单层1T'相过渡金属硫族化合物是一类新型的二维量子自旋霍尔绝缘体.其中,以单层1T'-WTe_(2)为代表的材料体系具有原子结构稳... 量子自旋霍尔效应通常存在于二维拓扑绝缘体中,其具有受拓扑保护的无耗散螺旋边界态.2014年,理论预言单层1T'相过渡金属硫族化合物是一类新型的二维量子自旋霍尔绝缘体.其中,以单层1T'-WTe_(2)为代表的材料体系具有原子结构稳定、体带隙显著、拓扑性质易于调控等许多独特的优势,对低功耗自旋电子器件的发展具有重要的意义.本文总结了单层1T'-WTe_(2)在实验上的最新进展,包括基于分子束外延生长的材料制备,螺旋边界态的探测及其对磁场的响应,掺杂、应力等手段在单层1T'-WTe_(2)中诱导出的新奇量子物态等.也对单层1T'-WTe_(2)未来可能的应用前景进行了展望. 展开更多
关键词 单层1T’-WTe_(2) 拓扑绝缘体 量子自旋霍尔效应 螺旋边界
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Applying Periodic Boundary Conditions to Predict Open Water Propeller Performance 被引量:3
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作者 王超 黄胜 +1 位作者 常欣 何苗 《Journal of Marine Science and Application》 2010年第3期262-267,共6页
Mathematical models of propellers were created that investigate the influence of periodic boundary conditions on predictions of a propeller's performance.Thrust and torque coefficients corresponding to different a... Mathematical models of propellers were created that investigate the influence of periodic boundary conditions on predictions of a propeller's performance.Thrust and torque coefficients corresponding to different advance coefficients of DTMB 4119, 4382, and 4384 propellers were calculated.The pressure coefficient distribution of the DTMB 4119 propeller at different sections was also physically tested.Comparisons indicated good agreement between the results of experiments and the simulation.It showed that the periodic boundary condition can be used to rationally predict the open water performance of a propeller.By analyzing the three established modes for the computation, it was shown that using the spline curve method to divide the grids can meet the calculation's demands for precision better than using the rake cutting method. 展开更多
关键词 PROPELLER open water performance periodic boundary condition pressure coefficient
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CIN85 associates with endosomal membrane and binds phosphatidic acid
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作者 Jing Zhang Xiudan Zheng Xiao Yang Kan Liao 《Cell Research》 SCIE CAS CSCD 2009年第6期733-746,共14页
CIN85 (Cbl-interacting protein of 85 kDa) is an important molecule involved in receptor tyrosine kinase endocytosis. Here we report that through its positively charged C-terminus, CIN85 associates with a fusogenic l... CIN85 (Cbl-interacting protein of 85 kDa) is an important molecule involved in receptor tyrosine kinase endocytosis. Here we report that through its positively charged C-terminus, CIN85 associates with a fusogenic lipid - phosphatidic acid. Its coiled-coil domain plays an important role in mediating this protein-lipid interaction. Deletion of the coiled-coil domain results in loss of membrane association, and reduced interaction with c-cbl, finally causing the blockage of epidermal growth factor receptor downregulation. In addition, a significant portion of CIN85 is located on the endosomal compartment and is related to endocytic cargo sorting, characterized by CIN85's localization on the "E class" compartment and EGF degradation blockage in CIN85 knockdown cells. Taken together, our results suggest that CIN85 may function as a scaffold molecule in both the internalization and endocytic cargo sorting processes through its association with the endosomal membrane. 展开更多
关键词 CIN85 the coiled-coil domain phosphatidic acid EGFR endocytosis ESCRT assembly
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Multigrid fictitious boundary method for incompressible viscous flows around moving airfoils
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作者 WAN De-Cheng 《Journal of Marine Science and Application》 2007年第2期51-58,共8页
In this paper, an efficient multigrid fictitious boundary method (MFBM) coupled with the FEM solver package FEATFLOW was used for the detailed simulation of incompressible viscous flows around one or more moving NAC... In this paper, an efficient multigrid fictitious boundary method (MFBM) coupled with the FEM solver package FEATFLOW was used for the detailed simulation of incompressible viscous flows around one or more moving NACA0012 airfoils. The calculations were carded on a fixed multigrid finite element mesh on which fluid equations were satisfied everywhere, and the airfoils were allowed to move freely through the mesh. The MFBM was employed to treat interactions between the fluid and the airfoils The motion of the airfoils was modeled by Newton-Euler equations. Numerical results of experiments verify that this method provides an efficient way to simulate incompressible viscous flows around moving airfoils. 展开更多
关键词 AIRFOILS induced-motion fictitious boundary method FEM MULTIGRID
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Tides and Turbulent Mixing in the North of Taiwan Island
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作者 Xiangzhou SONG Dexing WU Xiaohui XIE 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2019年第3期313-325,341,共14页
Microstructure and hydrological profiles were collected along two cross-shelf sections from the deep slope to the shallow water in the north of Taiwan Island in the summer of 2006.While the tidal currents on the shelf... Microstructure and hydrological profiles were collected along two cross-shelf sections from the deep slope to the shallow water in the north of Taiwan Island in the summer of 2006.While the tidal currents on the shelf were dominated by the barotropic tide with the current ellipse stretched across the shelf,significant internal tides were observed on the slope.The depth-mean turbulent kinetic energy(TKE)dissipation rate on the shelf was 10^-6W kg^-1,corresponding to a diapycnal diffusivity of 10^-2 m^2s^-1.The depth-mean TKE dissipation rate on the slope was 1×10^-7 Wkg^-1,with diapycnal diffusivity of 3×10^-4m^2s^-1.The shear instability associated with internal tides largely contributed to the TKE dissipation rate on the slope from the surface to 150 m,while the enhanced turbulence on the shelf was dominated by tidal or residual current dissipations caused by friction in the thick bottom boundary layer(BBL).In the BBL,the Ekman currents associated with the northeastward Taiwan Warm Current were identified,showing a near-bottom velocity spiral,which agreed well with the analytical bottom Ekman solution. 展开更多
关键词 microstructure observations turbulent mixing internal tides bottom boundary layer bottom Ekman spiral
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Study and Design of Spiral Bent Waveguide Configuration
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作者 ZENG Wen-hong LIAO Yun +2 位作者 SHI Shuang-jin QIU Qi LI Wei 《Semiconductor Photonics and Technology》 CAS 2007年第2期112-116,共5页
A new version of the scalar transverse electric(TE) wave equation in the bent waveguide is introduced. Then, TE polarized field in curved single-mode waveguides is analyzed by using the finite-difference beam propagat... A new version of the scalar transverse electric(TE) wave equation in the bent waveguide is introduced. Then, TE polarized field in curved single-mode waveguides is analyzed by using the finite-difference beam propagation method(FD-BPM). The bending loss in bent waveguides is gotten for the optical fields obtained from BPM and comparisons are made among losses of the waveguides with various curvature radiuses, refractive index differences and cross sections. Based on the results, the design of spiral bent waveguide configuration is proposed as follows: refractive index difference being of 0.007, both width and thickness of waveguides being of 6 μm, the curvature radius in the spiral centre being of 4 mm, and the bending loss coefficient of the designed spiral bent waveguide being of 0.302 3 dB/cm. 展开更多
关键词 finite differential beam propagation method transparent boundary condition effective index method bent waveguide
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