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1.
Some new solutions derived from the nonlinear (2+1)-dimensional Toda equation---an efficient method of creating solutions
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This paper presents a new and efficient approach for constructing
exact solutions to nonlinear differential--difference equations
(NLDDEs) and lattice equation. By using this method via symbolic
computation system MAPLE, we obtained abundant soliton-like and/or
period-form solutions to the (2+1)-dimensional Toda equation. It
seems that solitary wave solutions are merely special cases in one
family. Furthermore, the method can also be applied to other
nonlinear differential--difference equations. 相似文献
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从原子波包所满足的薛定谔方程出发,从理论上巧妙地推导出了原子干涉仪在重力的影响下所产生的相位差与重力加速度的关系表达式。提出了一种3×3阶的矩阵方法,以此来分析多个元件情况下原子干涉仪中的相位差,可以大大简化计算。利用这种方法不但能得到原子束在重力的影响下在自由空间中的传输矩阵,也可以得到原子束与π/2和π脉冲的相互作用矩阵。作为例子,用3×3阶矩阵方法计算了三脉冲原子干涉仪中的相位差,得出的结果与Wolf等对经典轨迹进行拉格朗日积分所得出的结果完全相符。进一步分析了五脉冲的原子干涉仪中的相位差,以说明3×3阶矩阵方法的简便性。 相似文献
3.
Carlos Avendaño 《Molecular physics》2013,111(9):1475-1486
Thermodynamic and structural properties of primitive models for electrolyte solutions and molten salts were studied using NVT and NPT Monte Carlo simulations. The Coulombic interactions were simulated using the Wolf method [D. Wolf, Phys. Rev. Lett. 68, 3315 (1992); D. Wolf, P. Keblinnski, S. R. Phillpot, and J. Eggebrecht, J. Chem. Phys. 110, 8254 (1999)]. Results for 1?:?1 and 2?:?1 charge ratio electroneutral systems are presented, using the restricted and non-restricted primitive models, as well as a soft PM pair potential for a monovalent salt [J.-P. Hansen and I. R. McDonald, Phys. Rev. A 11, 2111 (1975)] that has also been used to model 2?:?12 and 1?:?20 asymmetric colloidal systems, with size ratios 1?:?10 and 2?:?15, respectively [B. Hribar, Y. V. Kalyuzhnyi, and V. Vlachy, Molec. Phys. 87, 1317 (1996)]. We present the predictions obtained for these systems using the Wolf method. Our results are in very good agreement with simulation data obtained with the Ewald sum method as well as with integral-equation theories results. We discuss the relevance of the Wolf method in the context of variable-ranged potentials in molecular thermodynamic theories for complex fluids. 相似文献
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A novel method for enhancing light extraction efficiency of LEDs via diffraction of the lattice fabricated in ITO layers of LEDs is proposed. The lattice fabrication process includes holographic lithography and wet etching. 3-beam interference holographic approach was used to fabricate large-area hexagonal lattice mask which can cover 2-inch semiconductor wafer, and acid etching was used to transfer the lattice structure into p-contact ITO layer. 1.4 fold enhancement of light output at 20 mA injection current was obtained from GaN-based LEDs in the primary experiment. The lattice fabrication process is rapid and cost-effective thus enabling industrial mass production of high brightness LEDs. 相似文献
7.
The dissociated core structure of dislocation in two-dimensional triangular lattice is determined by the variational method
within lattice theory. The dissociation effect leads to a narrower core width of partial dislocations than the compact one.
The equilibrium separation between two partial dislocations is not very sensitive to the intrinsic stacking fault energy and
there exists deviation from the intrinsic stacking fault energy criterion in the continuous elastic theory of dislocation.
The relationship between the equilibrium separation and intrinsic stacking fault energy is analogous in lattice theory and
the Peierls-Nabarro model. But the equilibrium separation obtained in lattice theory is wider than that obtained in the Peierls-Nabarro
model for the same intrinsic stacking fault energy.
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8.
J.M. Dixon 《Solid State Communications》1979,30(10):657-659
The values of the Lea, Leask and Wolf parameters x, W, the off-diagonal matrix element of the vibrational Hamiltonian δ and the three independent coupling constants to Γ5 lattice modes have been calculated and shown to be consistent with inelastic neutron data and EPR field for resonance results. 相似文献
9.
采用格子Boltzmann方法对振动纤维捕集颗粒进行数值研究.纤维附近采用多块网格加细技术计算,颗粒采用Lagrange跟踪方法模拟.研究雷诺数为200的流向振动纤维绕流的AⅡ、AⅢ、AIV、S四种涡结构下的亚微米煤粉颗粒的捕集问题.结果表明纤维的流向强迫振动能够显著提高颗粒的捕集效率.且迎风面的捕集效率提升不大,背风面的提升则更为显著.颗粒撞击角度的统计反映了背风面捕集效率提升的细节.另外流动处于AⅢ模态时,每个周期内脱落两个正涡一个负涡,被捕集颗粒的初始位置分布不对称.而其它模态基本关于流场中心对称. 相似文献
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生物过滤技术因其具有有效性、低成本和环境友好等优点引起了人们的广泛关注.该技术主要通过生物过滤器去除含有H2S等废气的有毒有害气体.运用格子Boltzmann方法对三种生物过滤器模型中多孔介质的非均匀性流动进行了数值模拟.数值模拟结果表明,多孔介质的性质和进口流动条件对临界Rayleigh数有显著影响,临界Rayleigh数随着多孔介质的孔隙度和Darcy数的增大而逐渐变小,并随着进口Reynolds数的增大而逐渐变大.所得结果可望为生物过滤器的优化设计提供一个合理的理论依据. 相似文献
12.
This paper proposes two lattice traffic models by taking into
account the drivers' delay in response. The lattice versions of the
hydrodynamic model are described by the differential-difference
equation and difference-difference equation, respectively. The
stability conditions for the two models are obtained by using the
linear stability theory. The modified KdV equation near the critical
point is derived to describe the traffic jam by using the reductive
perturbation method, and the kink--antikink soliton solutions related
to the traffic density waves are obtained. The results show that the
drivers' delay in sensing headway plays an important role in jamming
transition. 相似文献
13.
The three-dimensional (3D) lattice Boltzmann models, 3DQ15, 3DQ19 and 3DQ27, under different wall boundary conditions and lattice resolutions have been investigated by simulating Poiseuille flow in a circular cylinder for a wide range of Reynolds numbers. The 3DQ19 model with improved Fillippova and Hanel (FH) curved boundary condition represents a good compromise between computational efficiency and reliability. Blood flow in an aortic arch is then simulated as a typical haemodynamic application. Axial and secondary fluid velocity and effective wall shear stress profiles in a 180° bend are obtained, and the results also demonstrate that the lattice Boltzmann method is suitable for simulating the flow in 3D large-curved vessels. 相似文献
14.
The properties of an ordering solid solution are substantially dependent on the long-range and short-range order parameters; a method is given for representing a binary solid solution as a set of cluster components whose short-range order parameters are incorporated out to the second coordination sphere. The scheme is illustrated via the lattice parameter and Debye temperature for Ti-Mo alloys (bcc lattice) and via the magnetic moment of Fe-Pd alloys (fcc lattice). The method allows one to describe nonmonotonic composition-property relationships and to define the values of properties for ordered structures.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 18–24, February 1978. 相似文献
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王新强 《原子与分子物理学报》1997,14(2):243-246
提出了一种基于密度泛函理论计算晶体结合能的变分法,利用该方法初步计算了LiF、NaF、KF、LiCl、NaCl和KCl这六种典型离子晶体的结合能、平衡晶格常数和体弹性模量,与实验结果进行了比较,分析了存在的问题,并指出了与其它同类方法相比该方法的优点 相似文献
18.
Multi-relaxation-time lattice Boltzmann front tracking method for two-phase flow with surface tension
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<正>In this paper,an improved incompressible multi-relaxation-time lattice Boltzmann-front tracking approach is proposed to simulate two-phase flow with a sharp interface,where the surface tension is implemented.The lattice Boltzmann method is used to simulate the incompressible flow with a stationary Eulerian grid,an additional moving Lagrangian grid is adopted to track explicitly the motion of the interface,and an indicator function is introduced to update the fluid properties accurately.The interface is represented by using a four-order Lagrange polynomial through fitting a set of discrete marker points,and then the surface tension is directly computed by using the normal vector and curvature of the interface.Two benchmark problems,including Laplace’s law for a stationary bubble and the dispersion relation of the capillary wave between two fluids are conducted for validation.Excellent agreement is obtained between the numerical simulations and the theoretical results in the two cases. 相似文献
19.
The density functional theory (DFT) is used to study the atomic interactions in transition metal-based interstitial alloys.
The strain field is calculated in the discrete lattice model using Kanzaki method. The total energy and hence atomic forces
between interstitial hydrogen and transition metal hosts are calculated using DFT. The norm-conserving pseudopotentials for
H, Cu and Pd are generated self-consistently. The dynamical matrices are evaluated considering interaction up to first nearest
neighbors whereas impurity-induced forces are calculated with M32H shell (where M = Cu and Pd). The atomic displacements produced by interstitial hydrogen at the octahedral site in Cu and
Pd show displacements of 7.36% and 4.3% of the first nearest neighbors respectively. Both Cu and Pd lattices show lattice
expansion due to the presence of hydrogen and the obtained average lattice expansion ΔV/V = 0.177 for Cu and 0.145 for Pd.
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