Parallel computation of the flow of integral viscoelastic fluids on a heterogeneous network of workstations

We consider the parallel computation of flows of integral viscoelastic fluids on a heterogeneous network of workstations. The proposed methodology is relevant to computational mechanics problems which involve a compute-intensive treatment of internal variables (e.g. fibre suspension flow and deformation of viscoplastic solids). The main parallel computing issue in such applications is that of load balancing. Both static and dynamic allocation of work to processors are considered in the present paper. The proposed parallel algorithms have been implemented in an experimental, parallel version of the commercial POLYFLOW package developed in Louvain-la-Neuve. The implementation uses the public domain PVM software library (Parallel Virtual Machine), which we have extended in order to ease porting to heterogeneous networks. We describe parallel efficiency results obtained with three PVM configurations, involving up to seven workstations with maximum relative processing speeds of five. The physical problems are the stick/slip and abrupt contraction flows of a K.B.K.Z. integral fluid. Using static allocation, parallel efficiencies in the range 67%–85% were obtained on a PVM network with four workstations having relative speeds of 2:1:1:1. Parallel efficiencies higher than 90% were obtained on the three PVM configurations using the dynamic load-balancing schemes.     

Engaging in problem posing activities in a dynamic geometry setting and the development of prospective teachers’ mathematical knowledge

In the present study we explore changes in perceptions of our class of prospective mathematics teachers (PTs) regarding their mathematical knowledge. The PTs engaged in problem posing activities in geometry, using the “What If Not?” (WIN) strategy, as part of their work on computerized inquiry-based activities. Data received from the PTs’ portfolios reveals that they believe that engaging in the inquiry-based activity enhanced both their mathematical and meta-mathematical knowledge. As to the mathematical knowledge, they deepened their knowledge regarding the geometrical concepts and shapes involved, and during the process of creating the problem and checking its validity and its solution, they deepened their understanding of the interconnections among the concepts and shapes involved. As to meta-mathematical knowledge, the PTs refer to aspects such as the meaning of the givens and their relations, validity of an argument, the importance and usefulness of the definitions of concepts and objects, and the importance of providing a formal proof.     

Bohr-Mottelson转动谱公式参数之间的新关系式

在利用Harris两参数公式研究Bohr-Mottelson转动谱公式参数之间的关系的基础上,改用Harris三参数公式,并由此提出了Bohr-Mottelson转动谱公式参数之间的新关系式,进而用I(I+1)四参数展开式计算了A～60,80,130,140,150,190区超形变偶偶核的基带和锕系和稀土区正常形变核基带,讨论了参数之间的关系,发现新关系式与实验较好地符合.     

单谐振腔外部Q值的计算方法

 通过对带有耦合器的单驻波腔进行等效电路分析,推导出可计算带有耦合波导的单谐振腔外部Q值的反射相位法,该方法通过计算不同频率的反射相位来确定谐振频率和外部Q值。详细叙述了在CST Microwave Studio中用谐振模式求解法、直接时域跟踪法和反射相位法进行计算的步骤;用这3种方法分别计算了二次发射微波电子枪的外部Q值并和实验测量结果做了比较。结果显示3种计算方法都有很高的精度,但反射相位法的速度最快,耗时1 071 s。计算发现外部Q值与耦合口长度的4.1次方成反比。     

用5种不同的电子光学软件对微波管电子枪进行模拟计算

 对TWTCAD微机版、工作站版本、EGUN,CAMEO以及Orprogr电子光学软件背景和特点作了一个简单介绍,并利用其模拟计算了11支不同结构的电子枪。将计算得到的导流系数、射程和注腰半径与实验数据列表对比,结果表明：不同电子光学软件计算不同类型电子枪其计算精度也不一样。在导流系数方面,EGUN和Orprogr的计算精度较高,绝对平均误差分别为7.18%和7.4%;在射程方面,TWTCAD的计算精度最高,绝对平均误差为5.69%;在注腰半径方面,Orprogr与实验值偏差较大,绝对平均误差为47.43%,而工作站版本的计算精度最高,绝对误差仅为2.29%。     

基于自适应预测滤波理论的模数转换器设计方法

基于自适应差分量化理论,提出了在不增加转换位数的情况下提高模数转换器（ADC）动态范围的一种设计方法。该方法通过量化输入与预测的差值来获得预测增益,从而扩大ADC的动态范围;通过差分量化值与预测值相加得到输出信号,并将该分别采用LMS和RLS算法进行处理,得到输入信号的预测值,计算机模拟结果证实,上述两种算法均能使模数转换器的动态范围提高约25dB.比较而言,RLS算法收敛速度更快,收敛性更好,但计算量较大.     

钢筋混凝土梁抗弯性能的数值模拟

摘 要：利用大型通用有限元软件ANSYS10.0,首先对钢筋混凝土试件梁采用了三维的建模方式,然后对其抗弯性能进行了非线性数值模拟,所模拟的量包括各临界荷载、挠度、应力分布、中和轴的移动等,模拟结果与实测值吻合得很好。该方法可以用来分析钢筋混凝土梁板构件的承载能力,也可以应用在某些院校的教学中。     

CAD软件在工程地质三维建模中的应用

如何快速、准确地建立地质体的三维模型一直是众多岩土工程数值模拟工作者所面临的难题。虽然三维地学模拟软件具有很好的三维地质建模能力,但是由于数据结构的差异,采用他们现行三维地学模拟软件建立的地质模型难以导入数值模拟分析软件中,以为相应工程问题的数值模拟服务。目前,随着各种CAD、CAM软件行业的的飞速发展,涌现出了许多优秀的三维建模软件,而且这些软件大都与现行数值分析软件有着良好的数据接口功能。据此,本文提出了采用现行CAD软件来建立工程地质体的三维模型,使得建立的模型达到既\"可视\"又\"可算\"的目的。将其应用于云南某高速公路边坡的三维建模中,证明了该法具有方便、快捷和合理等优点。     

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利用组态软件编程设计监控界面,监控节点通过与现场总线控制器及高压监控节点的通信,实现对极向场电源状态的实时、可靠监控,并经ODBC接口将状态数据发送至数据库节点备份。简述了电源监控系统的构成,及通过不同的通信协议实现实时数据传输和处理的过程。