A parallel and scalable algorithm for ADI method with pre-propagation and message vectorization

It is hard to implement the ADI method in an efficient way on distributed-memory parallel computers. We propose “P-scheme” which parallelizes a tridiagonal linear system of equations for the ADI method, but its effectiveness is limited to the cases where the problem size is large enough mainly because of the communication cost of the propagation phase of the scheme.

In order to overcome this difficulty, we propose an improved version of the P-scheme with “message vectorization” which aggregates several communication messages into one and alleviates the communication cost. Also we evaluate the effectiveness of message vectorization for the ADI method and show that the improved version of the P-scheme works well even for smaller problems and linear and super-linear speedups can be achieved for 8194 × 8194 and 16,386 × 16,386 problems, respectively.     

基于案例分析金字塔模型的主动运维案例体系建设

针对传统运维案例在经验共享和处置效率方面的不足及运维领域同类事件重复发生概率高、处置差异大的情况,提出一种案例分析金字塔模型,使用基于向量化解析和知识分层提取的素材库构建方法,实现由生产运维操作标准库、生产运行异常事件库到案例素材库再到案例教学库的自动生成转变,并以金字塔模型为基础,通过引入改进的趋势预测分析方法、案例推理"5R"模型和"4S"案例教学模式完善预警预测、辅助决策、案例教学相关应用,建立主动运维案例体系。实践结果表明,通过整个体系的推行,改变了企业信息系统运维被动应付的局面,同类事件占比逐年降低,事件响应时间和处置时间明显缩短,运维服务质量大幅提升。     

黑白图像的矢量化

通过向Ｉｎｔｅｒｎｅｔ网页中加入质量高、制作精美的动画,可以增加网页的生动性,提高其表现力。Ｉｎｔｅｒｎｅｔ上的一些应用,如远程教学等,也需要通过大量的动画来提高质量,增强效果,而用以往的动画制作系统所制作的动画的数据量往往很大,经Ｉｂｎｔｅｒｎｅｔ传送所需时间之长令人难以忍受,新的动画制作系统多使用矢量菜进行动画制作,为使动画制作更加方便,提高制作效率,希望能通过某种手段自动完成图像矢量化,针对     

Vc: A C++ library for explicit vectorization

It is an established trend that CPU development takes advantage of Moore's Law to improve in parallelism much more than in scalar execution speed. This results in higher hardware thread counts (MIMD) and improved vector units (SIMD), of which the MIMD developments have received the focus of library research and development in recent years. To make use of the latest hardware improvements, SIMD must receive a stronger focus of API research and development because the computational power can no longer be neglected and often auto‐vectorizing compilers cannot generate the necessary SIMD code, as will be shown in this paper. Nowadays, the SIMD capabilities are sufficiently significant to warrant vectorization of algorithms requiring more conditional execution than was originally expected for Streaming SIMD Extension to handle. The Vc library ( http://compeng.uni‐frankfurt.de/?vc ) was designed to support developers in the creation of portable vectorized code. Its capabilities and performance have been thoroughly tested. Vc provides portability of the source code, allowing full utilization of the hardware's SIMD capabilities, without introducing any overhead. Copyright © 2011 John Wiley & Sons, Ltd.     

人工神经网络的直线图素识别质量判别器

讨论矢量化直线图素识别质量的判别方法，采用BP网络，网络输入为反映直线图素识别质量的特征因子，网络输出为从斜率、线宽及直线端点的定位精确性等方面对直线图素识别质量的评价，BP网络经训练成为直线图素质量判别器．由于输入到网络中的各特征因子均是与线宽的相对比值，因此，该方法对扫描分辨率的影响不敏感，也很容易推广到其他图素类型．     

工程图纸矢量化中的线条轮廓跟踪法

在工程图纸矢量化中引入了平均链码和线条的概述，阐述了平均链码与直线链码的关系，提出了确定线条边界的切向和法向，线条检测，线条两侧同步跟踪以民折处理的方法。以此实现直线或微弯曲线的整条提取，跟踪的同时实现图文的磁量化速度和质量有较大的提高。     

点阵图形矢量化的高效方法——有向边界法

本文将点阵图的边缘定义为有向边界，并据此提出了分两步来实现点阵图矢量化的新方法－有向边界法，该法与其他方法相比，具有算法简单，运行时间短，效率高等优点。     

Evaluating vector data type usage in OpenCL kernels

Open Computing Language (OpenCL) is an open, functionally portable programming model for a large range of highly parallel processors. To provide users with access to the underlying platforms, OpenCL has explicit support for features such as local memory and vector data types (VDTs). However, these are often low‐level, hardware‐specific features, which can be detrimental to performance on different platforms. In this paper, we focus on VDTs and investigate their usage in a systematic way. First, we propose two different approaches (inter‐vdt and intra‐vdt) to use VDTs in OpenCL kernels, and show how to translate scalar OpenCL kernels to vectorized ones. After obtaining vectorized code, we evaluate the performance effects of using VDTs with two types of benchmarks: micro‐benchmarks and macro‐benchmarks. With micro‐benchmarks, we study the execution model of VDTs and the role of the compiler‐aided vectorizer on five devices. With macro‐benchmarks, we explore the changes of memory access patterns before and after using VDTs, and the resulting performance impact. Not only our evaluation provides insights into how OpenCL's VDTs are mapped on different processors, but it also indicates that using such data types introduces changes in both computation and memory accesses. Based on the lessons learned, we discuss how to deal with performance portability in the presence of VDTs. Copyright © 2014 John Wiley & Sons, Ltd.     

煤矿安全监控系统自诊断方法研究

为确保煤矿安全监控系统"监控有效、运行可靠",基于相关规程及规定建立了包含设备安装、配置达标、系统运行维护达标、系统异常统计分析和平台运行组件等合规性评判指标体系及准则。在运用开源GIS技术实现矿井安全监控系统巷道布置矢量化的基础上,结合监测数据,确定了各指标评判方法;研发了煤矿安全监控系统自诊断系统,并应用于煤矿,为及时自动甄别监控系统异常提供支撑。     

通风机特性曲线图形矢量化技术

针对目前通风机特性曲线图形矢量化主要采用手工描点采集数据,使用Excel或自主开发软件绘图,数据采集和图形绘制是分离的,效率低且无法保证拟合曲线与原曲线的重合度等问题,利用矢量化方法,以原图为底板对曲线进行定位离散,并自动绘制出矢量图形。在此基础上,讨论了曲线采集点的数目和拟合方程的次数对拟合曲线重合度的影响。应用研究表明,该软件的效率是常规方法的5倍以上,自动绘制的图形与原图基本吻合,可以在现场推广应用。