网络模拟软件脚本研究

介绍了3款主流网络模拟软件(NS2, OPNET, GLOMOSIM)的特点及机制。由于采用这3种软件的网络模拟都必须基于模拟脚本,对大规模网络和复杂网络对象的模拟手动编写脚本又十分困难,因此以NS2的模拟为例,针对其构建Tcl脚本过程中存在的困难,提出使用C++编写脚本生成程序,大大提高了Tcl脚本生成的效率和准确性。实验证明该方法是成功的。因为不同网络模拟软件的模拟脚本很相似,所以该方法和算法可以被基于其他网络模拟软件的网络模拟所使用,具有普遍使用价值。     

计算机模拟天然沸石阳离子交换过程

用VISAL FORTRAN语言编制了天然沸石阳离子交换过程的模拟程序，并对不同浓度一价金属离子交换进行了模拟，模拟结果与实验结果吻合较好。文中还对沸石结构和交换过程可视化模拟进行了研究，为检验沸石离子交换的工业化应用提供了新方法。     

转筒式干燥器圆弧抄板的模拟研究

对转筒式干燥器中圆弧型抄板的特性进行了研究，在所建立的数学模型的基础上，推导出了此种抄板在随转筒旋转过程中所持有的颗粒物料量的计算公式，对它所持有的物料量及其与最大持有物料量的比值进行了分析、研究，用VB语言编制了仿真程序，并对实际应用的一种转筒式干燥器进行了仿真计算，在四种不同的条件下，得出了仿真结果，结果表明对于颗粒物料所建立的数学模型是正确的，仿真结果与实际情况相吻合，该仿真程序对此类问题的研究具有参考价值。     

转筒干燥器直角抄板的模拟与试验研究

对转简式干燥器中直角型抄板的特性进行了研究，在所建立的数学模型的基础上，推导出此种抄板在随转简旋转过程中所持有的颗粒物料量的计算公式，对它所持有的物料量及其与最大持有物料量的比值进行了分析研究，用VB语言编制了仿真程序，并对实际应用的一种转简式干燥器进行了仿真计算，在三种不同的条件下，得出了仿真结果。结果表明对于颗粒物料所建立的数学模型是正确的，仿真结果与实际情况相吻合。该仿真程序对此类问题的研究具有参考价值。     

LTA型沸石吸附CO2的蒙特卡罗模拟研究

采用巨正则系综的蒙特卡罗(GCMC)方法研究了CO2在LTA型沸石上的吸附.研究表明经典力场不适合CO2/LTA沸石吸附体系.通过拟合实验数据得到一组优化力场参数.基于优化力场的模拟结果表明:二氧化碳主要吸附在4A沸石超笼的中心和超笼中Na 离子附近朝向中心的位置,能量分布图的相应位置也显示了较强的作用力.而对于5A沸石,由于8元环孔口处没有阳离子,二氧化碳主要吸附在八元环孔道中和八面沸石笼的中心.用优化力场计算了4A与5A沸石吸附二氧化碳的吸附热(273K),计算结果与文献值比较吻合.     

几种吡啶衍生物在八面沸石中吸附的分子模拟

碱性氮化物(如吡啶、喹啉等)在沸石分子筛上的吸附作用是催化裂化催化剂中毒的重要原因,吸附过程复杂,研究费时且费用高.本文采用巨正则蒙特卡罗方法(C,CMC)研究了373 K,473 K和573 K时吡啶、2,6-二甲基吡啶、2,4,6-三甲基吡啶在八面沸石分子筛中的吸附件能,得到了有关吸附平衡常数、吸附热、吸附等温线等信息.计算得到的吸附热顺序为:2,4,6-三甲基吡啶(64.2 kJ/mol)＞2,6-二甲基吡啶(59.6 kJ/mol)＞吡啶(49.3 kJ/mol),吸附热数值处于文献报道的范围内;在373 K、473 K时,吡啶的饱和吸附量高于其他两种衍生物,吸附等温线能够较好地用Langumir模型拟合;573 K时,2,6-二甲基吡啶的吸附量最高,吡啶的吸附量最低,吸附等温线能够很好地用Freundlich模型拟合.吡啶衍生物在八面沸石分子筛上的吸附热和吸附量不同是由于它们的碱性和分子结构不同造成的.模拟所得吸附数据对于生产、研发、设计具有指导意义.     

使用VB与C语言混合编程生成植物模拟图形

文章通过VB与C语言混合编程,实现了将C程序结果转化为VB中的图形,对该过程中出现的常见问题提出了实用的解决办法。并在此基础上,设计了一个基于分形方法的简易植物模拟系统。     

微机模拟处理pH络合滴定法研究——Ⅱ.终点确定方法和最佳实验条件模拟估计程序

本文利用简便的滴定过程模型,确立了微机模拟处理实验数据,方便、准确地求解络合滴定等当点的方法。设计了最佳实验条件模拟估计程序。该法测定Zn~(2+),Pb~(2+),Cu~(2+),Fe~(3+)结果的相对误差Δ<1％。pH=6-7时,测定Ca~(2+)的相对误差为-1.61％;σ<0.001mmol,(N=5)。     

多随机流的一类混合服务台排队系统模型的计算机模拟研究

本文讨论了一类多随机顾客流的串并联混合多服务台排队系统模型的计算机模拟，在多服务台串并联混合情形下建立了６类模拟模型，并给出模拟实列     

多随机流的一类后进先出混合服务台排队系统模型的计算机模拟研究

本文讨论了一类多随机顾客流的后进先出串并联混合多服务台排队系统模型的计算机模拟,在多服务台串并联混合情形下建立了六类模拟模型,并给出模拟实例。     

Parallel-architecture-directed program transformation

The widespread use of parallel machines has been hampered by the difficulty of mapping applications onto them effectively. The difficulty arises because current programming languages require the programmer to specify a problem to be solved at a low level of abstraction in an imperative form. Thus the programmer must immediately encode an architecture-specific algorithm detailing every communication and calculation. This process is prone to error and complicates the reuse of software.

An alternative approach is to specify the problem to be solved at a high-level in a functional language. Meaning-preserving program transformations can then be used to derive a parallel algorithm. Such algorithms can be run on parallel graph-reduction or dataflow machines which automatically exploit the implicit parallelism in a functional language program. Such automatic decomposition techniques, however, are not yet capable of fully yielding the extra performance offered by the parallel hardware.

We show how, by including an architecture specification with the problem specification, and extending the amount of transformation performed, it is possible to produce functional language code that explicity expresses the calculations and communications to be performed by the processors. This simplifies compilation, yields faster programs and enables parallel software to be developed for a wide variety of parallel computer architectures.

A goal-seeking transformation methodology has been developed which enables a high-level functional specification of the problem and a high-level functional abstraction of the target computer architecture to be systematically manipulated to produce an efficient parallel algorithm tailored to the target architecture. As the transformations start from very high-level specifications, the discovery of new algorithms is facilitated.

A case study is used to demonstrate the effectiveness of the technique. We show how a high level specification for sort can be transformed with a pipeline architecture specification to give a mergesort and how the same specification with a dynamic-message-passing architecture specification can be transformed to a novel parallel quicksort.     

Using computer vision to simulate the motion of virtual agents

In this paper, we propose a new model to simulate the movement of virtual humans based on trajectories captured automatically from filmed video sequences. These trajectories are grouped into similar classes using an unsupervised clustering algorithm, and an extrapolated velocity field is generated for each class. A physically‐based simulator is then used to animate virtual humans, aiming to reproduce the trajectories fed to the algorithm and at the same time avoiding collisions with other agents. The proposed approach provides an automatic way to reproduce the motion of real people in a virtual environment, allowing the user to change the number of simulated agents while keeping the same goals observed in the filmed video. Copyright © 2007 John Wiley & Sons, Ltd.     

烷烃在分子筛孔中吸附和扩散的分子模拟

用巨正则系综蒙特卡罗(grand canonical monte carlo,GCMC)和构型偏倚蒙特卡罗(configurational-bias monte carlo,CB- MC)相结合的模拟方法,研究300 K下,烷烃(甲烷、乙烷、丙烷、丁烷)在ISV、MEL型分子筛上的吸附,饱和吸附量的大小顺序为:甲烷>乙烷>丙烷>丁烷。模拟甲烷-乙烷、乙烷-丙烷混合物在分子筛(ISV、MOR、MEL型)中的吸附分离,结果甲烷-丙烷比乙烷-丙烷混合物更易分离。采用分子动力学(molecular dynamics,MD)模拟方法,研究甲烷在MEL、MOR分子筛上的扩散系数,分别为2.76-3.86 m~2·s~(-1)、3.14-13.30 m~2·s~(-1),烷烃在分子筛中的扩散与吸附相关,且扩散系数的大小与分子筛的结构有关。模拟所得的有关吸附扩散性质的数据对于化工生产、研发和设计具有指导意义。     

A method of program transformation between variable sharing and message passing

There have been proposed and used many programming concepts for realizing interprocess communication and synchronization, and two fundamental categories among them are variable sharing (e.g. semaphores) and message passing (signals, input/output in CSP and redezvous in Ada). The aim of this paper is to investigate the relationship between these two mechanisms, and in particular, program transformation between them. We here propose a transformation method between parallel programs written in each of these two, which uses transformation schemes named monitor transformations. We exhibit the method by showing through a chain of program transformations the equivalence of two versions of a parallel algorithm called dynamic sorting array.     

tmLQCD: A program suite to simulate Wilson twisted mass lattice QCD

We discuss a program suite for simulating Quantum Chromodynamics on a 4-dimensional space–time lattice. The basic Hybrid Monte Carlo algorithm is introduced and a number of algorithmic improvements are explained. We then discuss the implementations of these concepts as well as our parallelisation strategy in the actual simulation code. Finally, we provide a user guide to compile and run the program.

Program summary

Program title: tmLQCDCatalogue identifier: AEEH_v1_0Program summary URL::http://cpc.cs.qub.ac.uk/summaries/AEEH_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: GNU General Public Licence (GPL)No. of lines in distributed program, including test data, etc.: 122 768No. of bytes in distributed program, including test data, etc.: 931 042Distribution format: tar.gzProgramming language: C and MPIComputer: anyOperating system: any with a standard C compilerHas the code been vectorised or parallelised?: Yes. One or optionally any even number of processors may be used. Tested with up to 32 768 processorsRAM: no typical values availableClassification: 11.5External routines: LAPACK [1] and LIME [2] libraryNature of problem: Quantum ChromodynamicsSolution method: Markov Chain Monte Carlo using the Hybrid Monte Carlo algorithm with mass preconditioning and multiple time scales [3]. Iterative solver for large systems of linear equations.Restrictions: Restricted to an even number of (not necessarily mass degenerate) quark flavours in the Wilson or Wilson twisted mass formulation of lattice QCD.Running time: Depending on the problem size, the architecture and the input parameters from a few minutes to weeks.References:

• [1] 

  http://www.netlib.org/lapack/.

• [2] 

  USQCD, http://usqcd.jlab.org/usqcd-docs/c-lime/.

• [3] 

  C. Urbach, K. Jansen, A. Shindler, U. Wenger, Comput. Phys. Commun. 174 (2006) 87, hep-lat/0506011.

     

一种结合MDA的高阶模型转换方法

模型转换是MDA的关键技术,也是MDA的研究热点。目前,不同的MDA开发平台都有一套相对独立的开发技术和转换框架,这使平台之间缺乏兼容性,模型转换代码重用困难。究其原因是缺少一种与具体转换语言相对应,且与平台无关的转换规则模型。为了解决以上问题,将高阶模型转换的思想与模型驱动软件开发相结合,提出了一种构造模型转换规则的高阶转换元模型,并以ATL语言为例展示了高阶转换元模型的使用方法;最后通过一个实例验证了该方法的可行性和可用性。该方法提高了模型转换语言的抽象层次,降低了模型转换语言的重用难度,在一定程度上解决了模型转换技术不兼容的问题。     

A lumped conceptual model to simulate groundwater level time-series

Lumped, conceptual groundwater models can be used to simulate groundwater level time-series quickly and efficiently without the need for comprehensive modelling expertise. A new model of this type, AquiMod, is presented for simulating groundwater level time-series in unconfined aquifers. Its modular design enables users to implement different model structures to gain understanding about controls on aquifer storage and discharge. Five model structures are evaluated for four contrasting aquifers in the United Kingdom. The ability of different model structures and parameterisations to replicate the observed hydrographs is examined. AquiMod simulates the quasi-sinusoidal hydrographs of the relatively uniform Chalk and Sandstone aquifers most efficiently. It is least efficient at capturing the flashy hydrograph of a heterogeneous, fractured Limestone aquifer. The majority of model parameters demonstrate sensitivity and can be related to available field data. The model structure experiments demonstrate the need to represent vertical aquifer heterogeneity to capture the storage–discharge dynamics efficiently.     

BIOTURB: A FORTRAN program to simulate the effects of bioturbation on the vertical distribution of sediment

Bioturbation may have serious implications for preservation of original stratigraphic distribution of sediment. Thus, several methods have been developed to model the redistribution of sediment by bioturbation. The program BIOTURB provides a tool to compare and evaluate different models of bioturbation and their effects on sediment distribution. A flexible approach allowing changes in bioturbating fauna with time, fluctuation of sedimentation rate and sediment type deposited, selective sediment transport by organisms, both random and nonrandom mixing processes, and variation in intensity of mixing with depth was taken. This was achieved by using a transition matrix modeled after a bioturbating fauna in conjunction with a Monte Carlo procedure to govern the redistribution of sediment during mixing. The simulation model, FORTRAN program, and an example are described in detail.