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介绍了具有自主知识产权的蒙特卡罗(MC)粒子输运程序JMCT的初步研制成果。JMCT基于三维组合几何支撑软件框架JCOGIN,采用模块化,分成多层管理结构,可处理多群碰撞和连续能量碰撞,可进行粒子并行和区域分解并行两种并行方法,并具有良好的可扩展性和高速通信技术,同时配有可视化建模前处理软件。介绍了JMCT采用的多群物质碰撞机制,展示了程序模拟计算测试模型的结果,与MCNP程序计算结果一致。JMCT串行计算速度相比MCNP提高了约3 倍;在20 480个处理器核上模拟2109样本,并行效率可达70%。 相似文献
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研究了闪光X射线辐射照像蒙特卡罗程序(FXRMC)在MPI平台下的并行计算实现,给出了实现过程中并行随机数的产生方法。对并行程序的测试结果表明:并行程序与串行程序结果一致,加速比比较理想,呈线性增长,并行效率在16个处理器上可达80%以上。算例的结果说明了并行化可有效地解决程序计算散射技术性能时的耗时问题,从而有效化解FXRMC耗时和大规模计算的困难,提高了FXRMC程序的计算规模和计算速度,达到了研究要求。 (Institute of Fluid Physics, CAEP, P. O. Box 919-105, Mianyang 621900, China) 相似文献
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三维电磁粒子模拟基于时域有限差分算法(FDTD)和PIC(particle-in-cell)方法.根据FDTD和PIC方法的特点,可以将整个模拟区域分割为多个子区域,每个计算进程模拟计算一个子区域,通过消息传递交换子区域的边界数据从而实现并行计算这一基本思路,完成了并行算法的设计,并分析了并行加速比的影响因素.在三维电磁粒子模拟软件CHIPIC3D上实现了该并行算法并验证了算法的正确性,最后应用CHIPIC3D并行版本对磁绝缘线振荡器和相对论速调管两种典型的高功率微波源器件进行了模拟,证明了该并行算法能取
关键词:
电磁粒子模拟
时域有限差分
并行计算
高功率微波源 相似文献
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用区域分解算法结合蒙特卡罗法求坦克温度场和红外辐射出射度 总被引:3,自引:0,他引:3
本文将区域分解算法和蒙特卡罗法相结合,求坦克温度场和红外辐射出射度.采用蒙特卡罗法计算辐射传递系数,可以考虑界面的复杂辐射特性,如:镜反射、各向异性发射、各向异性反射等;可直接考虑界面的复杂几何特性,如:相互遮挡、太阳入射方向上的投影面积等.引入辐射传递系数,分离了计算的难点,使得在时间域(计算步骤)上能把整个问题分解为若干个子问题并行处理、在空间域(计算区域)上将坦克分解为若干个子区域,缩小计算规模,并可使用多个处理器并行计算;同时减轻了蒙特卡罗法编程的难度,缩短了计算时间. 相似文献
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介绍了NEPTUNE软件采用的一些并行计算方法:采用“块-网格片”二层并行区域分解方法,使计算规模能够扩展到上千个处理器核。基于复杂几何特征采用自适应技术并行生成结构网格,在原有规则区域的基础上剔除无效网格,大幅降低了存储量和并行执行时间。在经典的Boris和SOR迭代方法基础上,采用红黑排序和几何约束,提出了非规则区域上的Poisson方程并行求解方法。采用这些方法后,当使用NEPTUNE软件模拟MILO器件时,可在1 024个处理器核上获得51.8%的并行效率。 相似文献
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A. Weizenmann 《Physica A》2010,389(23):5416-5424
We study the effect of the dipolar coupling on the magnetic properties of two small interacting ferromagnetic particles. Each particle is a two-dimensional array of Ising spins with a central spin surrounded by a variable number of shells. The coupling between spins inside each particle is ferromagnetic and the dipolar interaction between the particles is determined as a function of the number of shells, temperature, and distance between their centers. We investigate the system by mean-field approximation and Monte Carlo simulations. The dipolar interaction is calculated in two ways, one assuming effective spins in the centers of the particles, and the other directly computing the interactions among all the pairs of spins, one in each particle. We show that the difference in the corresponding dipolar energies is a power law on the distance with exponent 5. We calculate the magnetization and susceptibility as a function of temperature, number of shells and distance between the particles’ centers. We show that the critical temperature increases with the number of spins in each particle, and it is more noticeable in the mean-field calculations than in the Monte Carlo simulations. 相似文献
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采用两路光子时间到达点构建光纤式光子计数伪随机码深度获取系统.为了研究降低深度误差的方法,以高斯函数为激光回波脉冲,计算瞬时概率密度函数,引入"时间行走"效应数学模型,推导深度误差克拉美罗下限.随着激光回波能量的增大,深度误差先降低再增大,并且码长越长,深度误差越小.采用理论推导的累积分布函数,生成光子时间到达点,蒙特卡洛仿真伪随机序列光子探测过程,结果大于理论数值模拟,符合克拉美罗下界原理.17组标定实验表明:由于目标表面特性的不同而导致探测到激光回波中光子数的浮动,该浮动引发光子"时间行走"效应,并带来伪随机码深度获取系统的互相关函数的整体偏移.采用数值拟合方程拟合不同光子计数比例值下的深度误差,测量得到的光子计数比例值,代入拟合的矫正方程,矫正后的深度均方误差下降至1cm. 相似文献
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A Quantum Monte Carlo investigation of a one-dimensional two band model with strong correlations in one band is presented. This two band model can be considered as a one-dimensional realization of the highT
c cuprates. In particular, the densities in the two bands, the formation of magnetic moments and the spin-spin correlations are studied as a function of particle number. The Quantum Monte Carlo results are compared with a simple mean field theory describing antiferromagnetic correlations, a variational Gutzwiller type calculation and a mapping to an effective one band model. 相似文献
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V. Ruiz Barlett J.J. Bigeón M. Hoyuelos H.O. Mártin 《Journal of computational physics》2009,228(16):5740-5748
We consider biased diffusion in a one-dimensional lattice and compare results obtained with fixed time step and kinetic Monte Carlo methods. Spurious dispersion and particle position correlation appear with the fixed time step Monte Carlo approach. The mentioned correlation increases with time. We demonstrate that the correct results, that correspond to a time step that tends to zero, are obtained using the kinetic Monte Carlo method. The conclusions also apply to biased diffusion in two or more dimensions and to random deposition. 相似文献
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Using the path integral Monte Carlo technique we show that semiconductor quantum rings with up to six electrons exhibit a temperature, ring diameter, and particle number dependent transition between spin ordered and disordered Wigner crystals. Because of the small number of particles the transition extends over a broad temperature range and is clearly identifiable from the electron pair correlation functions. 相似文献
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Macroscopic and microscopic long-distance bidirectional transfer depends on connections between entrances and exits of various transport mediums. Persuaded by the associations, we introduce a small system module of Totally Asymmetric Simple Exclusion Process including oppositely directed species of particles moving on two parallel channels with constrained entrances. The dynamical rules which characterize the system obey symmetry between the two species and are identical for both the channels. The model displays a rich steady-state behavior, including symmetry breaking phenomenon. The phase diagram is analyzed theoretically within the mean-field approximation and substantiated with Monte Carlo simulations. Relevant mean-field calculations are also presented. We further compared the phase segregation with those observed in previous works, and it is examined that the structure of phase separation in proposed model is distinguished from earlier ones. Interestingly, for phases with broken symmetry, symmetry with respect to channels has been observed as the distinct particles behave differently while the similar type of particles exhibits the same conduct in the system. For symmetric phases, significant properties including currents and densities in the channels are identical for both types of particles. The effect of symmetry breaking occurrence on the Monte Carlo simulation results has also been examined based on particle density histograms. Finally, phase properties of the system having strong size dependency have been explored based on simulations findings. 相似文献
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We offer a new proposal for the Monte Carlo treatment of many-fermion systems in continuous space. It is based upon diffusion Monte Carlo with significant modifications: correlated pairs of random walkers that carry opposite signs, different functions "guide" walkers of different signs, the Gaussians used for members of a pair are correlated, and walkers can cancel so as to conserve their expected future contributions. We report results for free-fermion systems and a fermion fluid with 14 3He atoms, where it proves stable and correct. Its computational complexity grows with particle number, but slowly enough to make interesting physics within the reach of contemporary computers. 相似文献
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We present here the results of our investigations of particle diffusion over different heterogeneous lattices with deep and shallow adsorption sites. A general analytical expression for chemical diffusion coefficient has been derived for a number of inhomogeneous lattices of different dimensionality and symmetry. We have calculated coverage dependencies of diffusion coefficients. The analytical data have been compared with the numerical data obtained by the kinetic Monte Carlo simulations. Almost perfect agreement between the respective results has been found. 相似文献