功率因数的概念及测试方法探讨

随着理论的发展和技术的进步，功率因数的概念有了更深的内涵，本文就其概念作了说明，对测量方法作了探讨。     

OpenMDSP: Extending OpenMP to Program Multi-Core DSPs

Abstract Multi-core digital signal processors （DSPs） are widely used in wireless telecommunication, core network transcoding, industrial control, and audio/video processing technologies, among others. In comparison with general-purpose multi-processors, multi-core DSPs normally have a more complex memory hierarchy, such as on-chip core-local memory and non-cache-coherent shared memory. As a result, efficient multi-core DSP applications are very difficult to write. The current approach used to program multi-core DSPs is based on proprietary vendor software development kits （SDKs）, which only provide low-level, non-portable primitives. While it is acceptable to write coarse-grained task-level parallel code with these SDKs, writing fine-grained data parallel code with SDKs is a very tedious and error-prone approach. We believe that it is desirable to possess a high-level and portable parallel programming model for multi-core DSPs. In this paper, we propose OpenMDSP, an extension of OpenMP designed for multi-core DSPs. The goal of OpenMDSP is to fill the gap between the OpenMP memory model and the memory hierarchy of multi-core DSPs. We propose three classes of directives in OpenMDSP, including 1） data placement directives that allow programmers to control the placement of global variables conveniently, 2） distributed array directives that divide a whole array into sections and promote the sections into core-local memory to improve performance, and 3） stream access directives that promote big arrays into core-local memory section by section during parallel loop processing while hiding the latency of data movement by the direct memory access （DMA） of a DSP. We implement the compiler and runtime system for OpenMDSP on PreeScale MSC8156. The benchmarking results show that seven of nine benchmarks achieve a speedup of more than a factor of 5 when using six threads.     

Providing Source Code Level Portability Between CPU and GPU with MapCG

Graphics processing units (GPU) have taken an important role in the general purpose computing market in recent years.At present,the common approach to programming GPU units is to write GPU specific cod...     

基于图划分的全基因组并行拼接算法

提出了一种基于图划分的全基因组并行拼接算法．该算法巧妙地将数据划分问题转化成图划分的问题，解决了传统数据划分算法中存在的节点负载不平衡的问题．同时，算法在建立关系图时有效地利用了WGS测序中所提供reads之间的长度信息和配对信息，使reads关系图能更准确地反映出数据之间的关系特性，从而提高了数据划分的准确性．实验结果表明，该算法可以准确地划分各种模拟数据、真实数据的数据集，相对于传统数据划分算法划分质量有了明显改善．     

生物信息学

生物信息学(Bioinformatics)是生物学、数学和计算机科学交叉所形成的一门学科,它主要是运用信息科学和计算技术的手段,通过数据分析和处理,揭示海量数据间的内在联系和生物学含义,进而提炼有用的生物学知识。由于生物信息学是在20世纪90年代才出现的一门新兴学科,因此,许多挑战和尚待解决的问题吸引了生物学家、数学家、统计学家、信息学家等众多学者的广泛关注。《计算机教育》在2006年4月期的杂志上刊登了密苏里大学哥伦比亚分校许东博士的一篇名为《生物信息学与计算机科学》的论文,许多老师反映良好,并要求本刊再多介绍一些相关知识。…     

阿里安5首飞失利与航天产业的高风险

阿里安５首飞失利与航天产业的高风险陈文光雨田（北京长征科技信息研究所）编者按阿里安５型运载火箭于１９９６年６月４日首飞失利，火箭连同携带的四颗卫星一并炸毁，造成５亿多美元的直接经济损失。下面简要介绍这种新型火箭的结构、性能、发射情况、事故调查结果，以...     

浙东南地区伊利石矿床及其找矿前景

本文阐述了浙东南地区伊利石矿床的产出特征;并按矿床产出形态,将其成因分为火山热蚀变交代型似层状矿床和火山气成热液蚀变充填型脉状矿床两类。该类矿床是火山岩中新发现,找矿前景广阔。     

基于可编程器件的模糊控制器

介绍了用硬件描述语言(VHDL)设计的一种新型的模糊控制系统，这种模糊控制器具有快速、修改方便的特点，给出了设计的框图和有关程序，并用FPGA来实现。     

坚持科学发展观 建设长江上游生态屏障

1989年，经国务院批准，我省被列为长江上游水土保持重点防治区。在党中央、国务院的正确领导下，在水利部、长江水利委员会的关心和指导下，我省启动了“治水兴蜀”工程，实施可持续发展战略，坚持以治理水土流失为重点的长江上游生态屏障建设。15年来，嘉陵江中下游、金沙江下游片区的南充、广安、乐山、凉山等15个市(州)，