共查询到20条相似文献,搜索用时 734 毫秒
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针对二维球坐标系下中子输运方程的SN算法, 提出基于(单元, 方向)二元组的有向图模型, 在已有的基于有向图的并行流水线算法基础上, 设计粒度可控多级并行SN算法。其中, 采用区域分解和并行流水线相结合的方式挖掘空间-角度方向的并行度, 提出能群流水并行方法, 并通过设置合适的流水线粒度来平衡有向图调度、通信和空闲等待开销。实验结果表明: 该算法可以有效地求解二维球坐标系下的中子输运方程。在某国产并行机1920核上, 对于96万网格、60个方向、24能群、数十亿自由度的典型中子输运问题, 获得了71%的并行效率。 相似文献
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辐射输运菱形差分SN方程的扩散综合加速方法 总被引:1,自引:1,他引:0
讨论辐射输运菱形差分SN方程的源迭代加速方法,在一维情形下给出与输运算子离散相容的线性多频灰体加速计算格式.数值算例表明该加速算法是健壮有效的. 相似文献
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介绍节块内嵌离散纵标(SN)方法求解三维堆芯中子输运/扩散方程的算法框架.在基于扩散理论的三维粗网节块展开方法(NEM)的算法体系中,用基于输运理论的径向二维细网节块离散纵标方法(NDOM)的内迭代过程,替代节块展开方法(NEM)内迭代的径向求解过程.该算法充分考虑了核电厂反应堆堆芯的三维结构特点,另一方面,也充分利用了已经成熟的三维粗网节块展开方法(NEM)和二维离散纵标方法(SN)的研究成果,同时有效避免了利用离散纵标方法(SN)求解三维中子输运方程所面临的计算内存和计算时间的瓶颈问题.编制开发二维多群节块离散纵标方法(NDOM)模块程序NSNM和三维多群节块展开方法(NEM)模块程序MGNEM,并以此为基础编制开发节块内嵌SN方法的模块程序HANWIND;其中,NSNM为HANWIND求解两维问题的功能模块.针对OECD/NEA-2D C5G7MOX基准问题以及两环路核电厂三维堆芯的数值验算结果表明,节块内嵌SN方法的算法开发及程序编制有效、切实可行. 相似文献
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将角通量分解成一个δ函数和一个低阶函数,分别采用解析方法和求积组来计算源项.利用δ函数SN方法,计算了平几何条件下含各向异性散射单速输运方程的临界问题.分析和数值结果表明,采用数量较少的离散方向,能够达到较高计算精度. 相似文献
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流体力学方程的间断有限元方法 总被引:9,自引:0,他引:9
在二维区域三角形网格上应用一阶、二阶和三阶精度间断有限元方法,对流体力学方程和方程组进行了数值模拟.计算结果与差分方法计算结果比较,认为间断有限元方法在求解复杂边界条件和区域问题上有一定的优势. 相似文献
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针对消防物联网系统中消防监控中心收到的火警信息存在延迟,可能导致救火作战时机延误的问题,提出了一种火警信息优先传输的解决方案。首先,推导出FCFS的M/M/1排队系统的运行指标;其次,将消防报警信息分为火警报警信息、火警消除信息、故障报警信息和故障消除信息等四个优先级,建立非抢占优先权排队系统,并推导出各个优先级的运行指标;最后,从平均逗留时间和平均队长两个维度,比较了非抢占优先权排队系统和M/M/1系统的性能。提出的火警信息优先传输方案,满足了火警信息时延小的要求,同时实现复杂度低,为消防物联网安全信息数据的获取提供一定的理论支撑。 相似文献
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Seung Ki Baek 《Physica A》2008,387(14):3660-3668
We study human dynamics by analyzing Linux history files. The goodness-of-fit test shows that most of the collected datasets belong to the universality class suggested in the literature by a variable-length queuing process based on priority. In order to check the validity of this model, we design two tests based on mutual information between time intervals and a mathematical relationship known as the arcsine law. Since the previously suggested queuing process fails to pass these tests, the result suggests that the modelling of human dynamics should properly consider the statistical dependency in the temporal dimension. 相似文献
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With rapid economic and social development, the problem of traffic congestion is getting more and more serious. Accordingly, network traffic models have attracted extensive attention. In this paper, we introduce a shortest-remaining-path-first queuing strategy into a network traffic model on Barabási–Albert scale-free networks under efficient routing protocol, where one packet’s delivery priority is related to its current distance to the destination. Compared with the traditional first-in-first-out queuing strategy, although the network capacity has no evident changes, some other indexes reflecting transportation efficiency are significantly improved in the congestion state. Extensive simulation results and discussions are carried out to explain the phenomena. Our work may be helpful for the designing of optimal networked-traffic systems. 相似文献
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Victorita Dolean Stéphane Lanteri Ronan Perrussel 《Journal of computational physics》2008,227(3):2044-2072
We present here a domain decomposition method for solving the three-dimensional time-harmonic Maxwell equations discretized by a discontinuous Galerkin method. In order to allow the treatment of irregularly shaped geometries, the discontinuous Galerkin method is formulated on unstructured tetrahedral meshes. The domain decomposition strategy takes the form of a Schwarz-type algorithm where a continuity condition on the incoming characteristic variables is imposed at the interfaces between neighboring subdomains. A multifrontal sparse direct solver is used at the subdomain level. The resulting domain decomposition strategy can be viewed as a hybrid iterative/direct solution method for the large, sparse and complex coefficients algebraic system resulting from the discretization of the time-harmonic Maxwell equations by a discontinuous Galerkin method. 相似文献
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首先,简单介绍了基于粘接元的无重叠区域分裂方法.这种方法利用变分原理,非常适合有限元近似.然后,着重讨论了这种区域分裂方法在求解不可压Navier-Stokes方程中的应用,具体包括等价变分公式的建立、通过算子分裂的时间离散、区域分裂情形下广义Stokes问题的共轭梯度迭代求解方法、空间的有限元离散.最后,以数值实验结果验证了这种区域分裂方法应用于不可压Navier-Stokes方程求解时的可靠性. 相似文献
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为了解决在数字散斑干涉技术测量时,散斑干涉相位条纹图像中大量噪声对相位解包裹结果和精度产生严重影响的问题,介绍了一种条纹正余弦分解和频域低通滤波结合的方法,实现了散斑干涉相位条纹图的高精度滤波。该方法的基本思路是在对相位图像进行滤波处理前,先将相位图通过正余弦函数进行映射转换成两幅图,分别经过频域滤波,然后再合成为相位图。这种分解频域滤波方法可以在滤波的同时,有效保留相位跳变信息。实验结果表明:与传统的图像降噪方法相比,该方法能够在保留图像“尖峰”信息的基础上,较好地滤除图像中的散斑噪声,方法简单有效,有效解决了传统滤波方法应用在相位条纹图中,相图灰度信息丢失10%~40%的问题。 相似文献
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In this paper, we develop an efficient splitting domain decomposition method (S-DDM) for compressible contamination fluid flows in porous media over multiple block-divided sub-domains by combining the non-overlapping domain decomposition, splitting, linearization and extrapolation techniques. The proposed S-DDM iterative approach divides the large domain into multiple block sub-domains. In each time interval, the S-DDM scheme is applied to solve the water head equation, in which an efficient local multilevel scheme is used for computing the values of water head on the interfaces of sub-domains, and the splitting implicit scheme is used for computing the interior values of water head in sub-domains; and the S-DDM scheme is then proposed to solve the concentration equation by combining the upstream volume technique. Numerical experiments are performed and analyzed to illustrate the efficiency of the S-DDM iterative approach for simulating compressible contamination fluid flows in porous media. The developed method takes the excellent attractive advantages of both the non-overlapping domain decomposition and the splitting technique, and reduces computational complexities, large memory requirements and long computational durations. 相似文献
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Ideas and tools from statistical physics have recently been applied to the investigation of human dynamics. The timing of human activities, in particular, has been studied both experimentally and analytically. Empirical data show that, in many different situations, the time interval separating two consecutive tasks executed by an individual follows a heavy-tailed probability distribution rather than Poisson statistics. To account for this data, human behaviour has been viewed as a decision-based queuing system where individuals select and execute tasks belonging to a finite list of items as an increasing function of a task priority parameter. It is then possible to obtain analytically the empirical result P(τ)∼1/τ, where P(τ) is the waiting time probability distribution.Here a continuous model of human dynamics is introduced using instead an infinite queuing list. In contrast with the results obtained by other models in the finite case we find a waiting time distribution explicitly depending on the priority distribution density function ρ. The power-law scaling P(τ)∼1/τ is then recovered when ρ is exponentially distributed. 相似文献