3DFD Simulation of Asymmetric Wave Field by Side-wall Acoustic Tool in Open and Cased Wells

1. Introduction Side-wall acoustic logging tools, such as the Segmented Bond Tool (SBT) from Baker Atlas and the tools for open hole measurements, utilize acoustic transducers mounted on six pads to make compensated acoustic velocity and attenuation measurements which are not affected by mud weight, gas cut, fast formation effects, casing surface conditions or reasonable tool de- centralizing. Studies on the wave fields generated by these tools are very important to tool design and data int…     

基于多核的OpenMp并行程序设计

介绍多核计算的出现和一种面向共享存储器的多处理器多线程并行编程语言OpenMp,然后再以一个实例来说明OpenMp在多核下如何进行并行程序设计,通过计算加速比说明使用OpenMp编程后程序执行效率得到显著提高。     

超线程技术以及H.264编码器中的并行运算分析

根据H,264这一新的视频压缩标准的特点，利用Intel的超线程技术以及OpenMp，可以使软件编码器进行线程级的并行运算，从而大大提高编码速度。该文对超线程技术、OpenMp以及编码过程中不同级别的并行运算进行了分析。证明了利用OpenMP对H.264编码器进行并行处理优化，再加上具有超线程技术的处理器的支持，必将会大大提高编码器的性能。     

三维复杂渗流场的并行求解

建立了基于水头和饱和度分布的双变量三维复杂渗流场饱和-非饱和计算模型,并通过分析数据执行时的相关性、算法固有的串行性及计算的耗时分布,在串行程序的基础上应用OpenMp并行编程接口实现了并行计算.分别对不同网格规模进行了并行数值模拟并测定了加速比,可以看出并行加速比与参与计算的处理器的个数呈线性分布,并且随着问题规模的增加而逐渐提高.同时也证明了数学模型的合理性.     

A parallel computational framework to solve flow and transport in integrated surface–subsurface hydrologic systems

Hydrologic modeling requires the handling of a wide range of highly nonlinear processes from the scale of a hill slope to the continental scale, and thus the computational efficiency of the model becomes a critical issue for water resource management. This work is aimed at implementing and evaluating a flexible parallel computing framework for hydrologic simulations by applying OpenMP in the HydroGeoSphere (HGS) model. HGS is a 3D control-volume finite element model that solves the nonlinear coupled equations describing surface–subsurface water flow, solute migration and energy transport. The computing efficiency of HGS is improved by three parallel computing schemes: 1) parallelization of Jacobian matrix assembly, 2) multi-block node reordering for performing LU solve efficiently, and 3) parameter privatization for reducing memory access latency. Regarding to the accuracy and consistency of the simulation solutions obtained with parallel computing, differences in the solutions are entirely due to use of a finite linear solver iteration tolerance, which produces slightly different solutions which satisfy the convergence tolerance. The maximum difference in the head solution between the serial and parallel simulations is less than 10⁻³ m, using typical convergence tolerances. Using the parallel schemes developed in this work, three key achievements can be summarized: (1) parallelization of a physically-based hydrologic simulator can be performed in a manner that allows the same code to be executed on various shared memory platforms with minimal maintenance; (2) a general, flexible and robust parallel iterative sparse-matrix solver can be implemented in a wide range of numerical models employing either structured or unstructured mesh; and (3) the methodology is flexible, especially for the efficient construction of the coefficient and Jacobian matrices, compared to other parallelized hydrologic models which use parallel library packages.