Steady motion of the magnetic vortex under the magnus force in weak ferromagnets

The problem of steady motion of the magnetic vortex in a moving domain wall under the action of the Magnus force in weak ferromagnets was studied. Dynamic bending of the domain wall containing a moving vortex was analyzed. The formulas describing the dependences of the vortex velocity on the velocity of the domain wall in which it moves were derived.     

在冲力作用下台球运动的力学分析

作为刚体运动的例证,讨论了在冲力作用下台球的运动情形,计算了在不同的击打条件下,台球进入无滑滚动状态的绕质心转动的速度.     

Quantum treatment of the time-dependent coupled oscillators under the action of a random force

In this communication we introduce the problem of time-dependent frequency converter under the action of external random force. We have assumed that the coupling parameter and the phase pump are explicitly time dependent. Using the equations of motion in the Heisenberg picture the dynamical operators are obtained, however, under a certain integrability condition. When the system is initially prepared in the even coherent states the squeezing phenomenon is discussed. The correlation function is also considered and it has been shown that the nonclassical properties are apparent and sensitive to any variation in the integrability parameter. Furthermore, the wave function in Schrödinger picture is calculated and used it to derive the wave function in the coherent states. The accurate definition of the creation and annihilation operators are also introduced and employed to diagonalize the Hamiltonian system.     

Numerical calculations of the driving force on an Abrikosov vortex

The driving force on an Abrikosov vortex is calculated numerically from the London equation and involved energies for a vortex perpendicular to the screening current near the surface of a superconductor. Compared with previous analytical derivation of the total force, the partial magnetic, kinematic, and external forces are also obtained so that the nature of the driving force may be deeply discussed. It is shown that the force is neither a Lorentz force nor a Magnus force as often believed and that in order to get a correct result, the image effects and the work done by the applied field must be taken into account. A name of London force is suggested for the driving force. A deep understanding of the nature of the driving force on Abrikosov vortices may also be important in the study of vortex pinning and dynamics in type-II superconductors.     

关于质点弹簧系统在重力作用下的静平衡与振动

质点弹簧系统在重力作用下的静平衡状态由此系统的有效质量决定;其本征振动频率wn则由弹簧与质点的质量之比ml/m2 决定;Wn的平均值w与w2由此系统的初始条件决定,不同的初始条件导致不同的平均值.例如,若u(y,O)=uαf(y)=uaf(y)=u0y,则可得w2=k/(m2+1/3m1).并给出一个计算θ1:w1/w0的近似公式.     

Numerical simulation of flat-tip micro-indentation of glassy polymers: Influence of loading speed and thermodynamic state

Flat-tip micro-indentation tests were performed on quenched and annealed polymer glasses at various loading speeds. The results were analyzed using an elasto-viscoplastic constitutive model that captures the intrinsic deformation characteristics of a polymer glass: a strain-rate dependent yield stress, strain softening and strain hardening. The advantage of this model is that changes in yield stress due to physical aging are captured in a single parameter. The two materials studied (polycarbonate (PC) and poly(methyl methacrylate) (PMMA)) were both selected for the specific rate-dependence of the yield stress that they display at room temperature. Within the range of strain rates experimentally covered, the yield stress of PC increases linearly with the logarithm of strain rate, whereas, for PMMA, a characteristic change in slope can be observed at higher strain rates. We demonstrate that, given the proper definition of the viscosity function, the flat-tip indentation response at different indentation speeds can be described accurately for both materials. Moreover, it is shown that the model captures the mechanical response on the microscopic scale (indentation) as well as on the macroscopic scale with the same parameter set. This offers promising possibilities of extracting mechanical properties of polymer glasses directly from indentation experiments.     

Numerical simulation of the vortex dynamics in the two-band Ginzburg-Landau model

The dynamics of Abrikosov vortices in the intermediate state of a two-band superconductor is analyzed by numerical simulation of the nonstationary two-band Ginzburg-Landau equations.     

器壁旋转模式下液体平衡状态的分析

基于器壁带动液体旋转稳定后形成的抛物面,推导出器壁斜率为K(K≠0)时的恒等式.得出K→∞时,随着转速增加,液位的变化是无限的,液位的上升高度与下降深度恒相等,旋转抛物体与同底同高圆柱体积关系为定值;当K＞0时,容器为上大下小的圆筒,旋转抛物面导致的液位变化是有限的,存在的极限值为√3+1,当液体旋转角速度超过临界角速...     

声波作用下球形颗粒外声流分布的数值模拟

综合考虑声学边界层内的热损失和黏性损失,建立处于平面驻波声压波节位置二维球形颗粒外声流计算模型,利用分离时间尺度的数值方法对颗粒外声流流场特征进行模拟。将模拟结果与相应的解析解和实验结果对比,验证了数值模拟的可靠性。在此基础上,研究了雷诺数Re和斯特劳哈尔数Sr对球形颗粒声学边界层内二阶声流流场结构、涡流强度及范围的影响规律。结果表明,随Sr和Re增大,声学边界层内的涡流结构尺度呈指数形式减小,其涡流尺度与颗粒直径D和激励频率f成反比,与流体介质运动黏度v成正比;且满足低Sr和高Re的声振系统可形成范围较大、更强烈的声流运动。该数值方法可用于对任意物理模型外声流特性的评估。     

Numerical simulation of acoustic streaming distribution outside spherical particles under the action of sound waves

Considering the heat loss and viscosity loss inside the acoustic boundary layer,an acoustic streaming calculation model outside a two-dimensional spherical part...     

Numerical simulation of the XY-model on a two-dimensional random lattice

We discuss a numerical simulation of the planar XY-model on a two-dimensional random lattice. Results obtained on the random lattice are compared with those obtained using identical methods on a square lattice, which acts as a “control experiment”. Calculations were made of the average energy per spin, susceptibility per spin and magnetization. The specific heat was obtained by a numerical differentiation of the energy curve. Also, the number of positive (or negative) spin vortices in the system at different temperatures was calculated. Particular attention is paid to the way in which these vortices entered the system, since it is their appearance which signals the phase transition. Numerical results computed at high temperatures are compared with the theoretical values obtained from high-temperature expansions; and those computed at low temperatures, with the results of spin-wave theory. We investigate the effect of varying the weights for the field theory on the random lattice.     

涡流管内三维强旋转流场数值模拟与分析

涡流管内可压缩气体的强旋转流动是涡流管能量分离的根本原因和驱动力,因而涡流管内流场研究是揭示涡流管能量分离物理机制的首要关键问题。由于涡流管内可压缩气体的三维强旋转湍流流动,实验测量中存在诸多问题,而CFD数值模拟技术对此具有很大的优势。文中以涡流管内部流场为研究对象,建立了涡流管计算域模型并进行网格划分,讨论了边界条件、湍流模型以及线性方程组求解策略等问题,对不同冷气流率下的涡流管内三维强旋流流场结构特性进行数值模拟,获得了不同冷气流率下的旋转运动、轴向运动、径向运动和循环流的分布特性。研究表明Realizableκ-ε湍流模型能够充分反映强旋流动特点,数值模拟结果与文献中实验值基本吻合。     

Explicit solution of diffusion master equation under the action of linear resonance force via the thermal entangled state representation

Using the well-behaved features of the thermal entangled state representation, we solve the diffusion master equation under the action of a linear resonance force, and then obtain the infinitive operator-sum representation of the density operator. This approach may also be effective for treating other master equations. Moreover, we find that the initial pure coherent state evolves into a mixed thermal state after passing through the diffusion process under the action of the linear resonance force.     

从头算方法研究面心立方铝在高温高压下的热力学状态方程

用从头算方法优化计算了面心立方铝的电子结构和总能,得到了它在零温下的状态方程和弹性性质.将得到的总能与晶格体积拟合到Debye模型,获得了非平衡态下的Gibbs自由能与温度、压力之间的关系,在此基础上计算了相应的热状态方程,利用Burakovsky-Preston-Silbar （BPS） 熔化模型计算了铝的熔化曲线.所有的电子结构和总能计算都是基于局域密度近似（LDA）和广义梯度近似（GGA）的平均得到的.计算得到的铝在高温、高压下的状态方程与一些热力学性质和熔化曲线同冲击波和静高压实验数据在225 G 关键词： 铝 热力学状态方程 从头算 熔化曲线     

HL-2A装置改造方案磁流体平衡的数值模拟

对HL-2A装置的改造方案进行数值模拟,获得了放电初始阶段零场区域设计的最佳方案、等离子体限制器平衡位形、单零偏滤器平衡位形和双零偏滤器平衡位形以及从气体击穿到等离子体电流平顶的等离子体平衡位形的演化过程。计算结果表明,该装置设计方案能够满足装置预期的设计参数要求。     

Redistribution of magnetospheric ions under the action of Miller force

Ponderomotive redistribution of ions along geomagnetic field lines is analyzed within the frame-work of a simple model of diffusion equilibrium of a multicomponent plasma. Miller force prevails in the case of Alfvén waves. This also takes place in the case of ion-cyclotron waves at the low-frequency limit. Qualitative analysis of the equations with allowance for satellite-based data on wave intensity shows significant redistribution of magnetospheric plasma due to Miller force.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 4, pp. 464–471, April, 1996.This paper was supported in part by the Russian Foundation for Fundamental Research (Project Code 94-05-16173a).     

一类非线性相对转动周期系统的平衡稳定性分析

利用一类周期性变系数线性常微分方程解的基本矩阵的Jordan形，分析一类非线性相对转动系统扭转的运动稳定性，从而得到非线性相对转动周期系统的运动稳定准则. 运用Lyapunov函数法，对广泛存在的一类机械传动系统的相对转动运动的平衡稳定位置的稳定域进行研究，并给出数学解析表达式. 这为工程中广泛存在的这类机械传动系统稳定工作区间工作参数的选取和相似模拟提供了理论依据及方法，据此可进一步分析和评价大型复杂旋转机械主传动系统的扭振稳定性. 关键词： 相对转动 相似模拟 运动稳定 平衡稳定     

相变前的热力学平衡态对铁电液晶排列的影响

本实验选用ZLI-3654型铁电液晶(FLC)以及SE-3140型取向剂制备FLC器件样品,通过改变FLC相变过程中的降温速率以及相变前的热力学平衡态来研究FLC相变前的热力学平衡态对FLC排列的影响,共进行了十组实验.实验后,将FLC器件静态对比度进行比较,得出手性向列相到近晶A相(N^*-SmA)相变前的热力学平衡态对FLC实现均匀排列起着极其重要的作用的结论.实验结果表明:器件的静态对比度可高达620 ∶1, N^*-SmA相变前的热力学平衡态有利于形成高对比 关键词： 铁电液晶 降温速率 热力学平衡态 高对比度