排序方式: 共有32条查询结果,搜索用时 656 毫秒
1.
2.
3.
在反应堆pin-by-pin精细建模及蒙特卡罗模拟计算研究中, 由于不同栅元的功率密度差异较大, 导致蒙特卡罗方法临界计算的样本在不同栅元之间的分配不均衡, 由此引起栅元内的各种计数的统计误差差异较大. 为使大部分栅元内计数的统计误差降至一个合理的水平, 单纯增加总样本已不是一个高效的解决方法. 通过在特定临界计算迭代算法的基础上改进并实现均匀裂变源算法的思想, 对大亚湾压水堆pin-by-pin模型取得了具有较高效率的数值结果. 本工作为具有自主知识产权的蒙特卡罗粒子输运模拟软件JMCT最终达到反应堆pin-by-pin模型(包括一系列国际基准模型)的模拟性能要求提供了一个有效的工具. 相似文献
4.
We introduce the potential-decomposition strategy (PDS), which can be used in Markov chain Monte Carlo sampling algorithms. PDS can be designed to make particles move in a modified potential that favors diffusion in phase space, then, by rejecting some trial samples, the target distributions can be sampled in an unbiased manner. Furthermore, if the accepted trial samples are insumcient, they can be recycled as initial states to form more unbiased samples. This strategy can greatly improve efficiency when the original potential has multiple metastable states separated by large barriers. We apply PDS to the 2d Ising model and a double-well potential model with a large barrier, demonstrating in these two representative examples that convergence is accelerated by orders of magnitude. 相似文献
5.
6.
对于非定常输运问题提出了一种基于香农熵的自动调整样本数策略。将每一计算步的总样本数划分为若干批并逐步模拟每批中的粒子, 可以在每批粒子模拟结束后通过计算得到该时间步幸存粒子属性分布对应的香农熵值。采用在线收敛性诊断方法, 一旦通过香农熵值序列判断对应的幸存粒子属性分布已经收敛, 则可以提前结束本时间步的计算。对一个空间一维非定常输运模型的计算结果表明, 该策略可以显著减少每一计算步的实际样本数且保持最终的结果基本不变, 从而减少了计算时间, 提高了计算效率。 相似文献
7.
本文用真空热蒸镀的方法得到了表面处有微量氧污染的有序表面合金,并用AES,LEED和HREELS研究了CO在该合金表面上的吸附。合金在52,75和105meV处产生三个振动峰,它们分别对应于表面上和表面Al原子以下的Al和氧原子之间的伸缩振动,在室温和低温下(135K),CO分子直立吸附在合金表面Ni原子顶位和最近邻的两个Ni原子桥位上并在250meV 和222meV处产生相应的损失峰。CO暴露量太子2.0L以后,105meV的损失峰强度随CO暴露量的增加有明显的增加,这是由于吸附在表面的CO有部分分解,分解后的氧原子和Al原子结合优先占据表面以下的位置,CO的分解速率与氧污染的多少有关,氧原子越多,分解速率越快。据我们所知,这是第一次在室温下观察到在Ni-Al合金表面上CO的分解。 相似文献
8.
New exact periodic solutions to (2+1)-dimensional dispersive long wave equations 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In this paper, we make use of the auxiliary equation and the expanded mapping methods to find the new exact periodic solutions for (2+1)-dimensional dispersive long wave equations in mathematical physics, which are expressed by Jacobi elliptic functions, and obtain some new solitary wave solutions (m → 1). This method can also be used to explore new periodic wave solutions for other nonlinear evolution equations. 相似文献
9.
10.
We propose a five-parameter dumbbell model to describe the fusion and fission processes of massive nuclei, where the collective variables are: the distance ρ between the center-of-mass of two fusing nuclei, the neck parameter ν, asymmetry D, two deformation variables β1 and β2 . The present model has macroscopic qualitative expression of polarization and nuclear collision of head to head, sphere to sphere, waist to waist and so on. The conception of the "projectile eating target" based on open mouth and swallow is proposed to describe the nuclear fusion process, and our understanding of the probability of fusion and quasi-fission is in agreement with some previous work. The calculated fission barriers of a lot of compound nuclei are compared with the experimental data. 相似文献