Revisiting the Parallel Strategy for DOACROSS Loops

Journal of Computer Science and Technology - DOACROSS loops are significant parts in many important scientific and engineering applications, which are generally exploited pipeline/wave-front...     

电雷管中电极塞平行度检测方法

针对传统的小尺寸电雷管人工检测方式耗时耗力,容易带入人工误差等问题,提出一种电雷管中电极塞平行度检测方法.该方法通过设计平行检测装置结构,利用高精度位移传感器,通过其对位移数据的记录,检测电极塞的平行度,实现高精度、自动化检测产品平行度.实验结果表明:该装置能够实现自动化、高精度的平行度检测,检测的重复精度基本能够达到μ级,满足检测精度要求.     

基于Spark SQL的分布式全文检索框架的设计与实现

随着信息化的深入,大数据在各个领域产生了巨大的价值,海量数据的存储和快速分析成为新的挑战。传统的关系型数据库由于性能、扩展性的不足以及价格昂贵等方面的缺点,难以满足大数据的存储和分析需求。Spark SQL是基于大数据处理框架Spark的数据分析工具,目前已支持TPC-DS基准,成为大数据背景下传统数据仓库的替代解决方案。全文检索作为一种文本搜索的有效方式,能够与一般的查询操作结合使用,提供更加丰富的查询和分析操作。目前,Spark SQL仅支持简单的查询操作,不支持全文检索。为了满足传统业务迁移和现有业务的使用需求,提出了分布式全文检索框架,涵盖了SQL文法、SQL翻译转换框架、全文检索并行化、检索优化4个模块,并在Spark SQL上进行了实现。实验结果表明相比于传统的数据库,在两种检索优化策略下,该框架的索引构建时间、查询时间分别减少到传统数据库的0.6%/0.5%和1%/10%,索引存储量减少为传统数据库的55.0%。     

光电综合标校系统光轴平行度标校方法

针对光电综合标校系统的功能组成及标校原理,提出了标校靶标的设计及标校方法,并利用感光相纸对激光光斑进行聚焦采集,实现了对电视/红外/激光三者光轴一致性的标校,检测结果验证了该标校靶标及标校方法的可行性和有效性。     

CAWR: Buffer Replacement with Channel‐Aware Write Reordering Mechanism for SSDs

A typical solid‐state drive contains several independent channels that can be operated in parallel. To exploit this channel‐level parallelism, a variety of works proposed to split consecutive write sequences into small segments and schedule them to different channels. This scheme exploits the parallelism but breaks the spatial locality of write traffic; thus, it is able to significantly degrade the efficiency of garbage collection. This paper proposes a channel‐aware write reordering (CAWR) mechanism to schedule write requests to different channels more intelligently. The novel mechanism encapsulates correlated pages into a cluster beforehand. All pages belonging to a cluster are scheduled to the same channels to exploit spatial locality, while different clusters are scheduled to different channels to exploit the parallelism. As CAWR covers both garbage collection and I/O performance, it outperforms existing schemes significantly. Trace‐driven simulation results demonstrate that the CAWR mechanism reduces the average response time by 26% on average and decreases the valid page copies by 10% on average, while achieving a similar hit ratio to that of existing mechanisms.     

一种连续变焦距电视的变倍补偿机构设计

为了实现电视的焦距连续变化,设计了一种连续变焦距电视的变倍补偿机构。提出了一种提高变倍、补偿机构运动精度的方法,实测两机构直线运动精度均为15″。通过靶场试验证明连续变焦距电视的变倍补偿机构的运动精度满足电视捕获、跟踪目标的精度要求,两直线滑轨平行度调整机构设计、加工简单,可以在其它直线运动机构中得到推广应用。     

Sorting-Based Calculation of Zeroes and Extrema of Functions as Applied to Search and Recognition. I

A stable address sorting is used for approximate calculation of zeroes and extrema of functions of one variable and two variables. In particular, the paper gives a new method for localization and approximate calculation of all the roots of a polynomial with arbitrary power. The method includes poorly separated roots, and its distinctive features are the computational stability and the maximum parallelism.     

A stencil of the finite-difference method for the 2D convection diffusion equation and its new iterative scheme

The paper gives the numerical stencil for the two-dimensional convection diffusion equation and the technique of elimination, and builds up the new iterative scheme to solve the implicit difference equation. The scheme's convergence and its higher rate of convergence than the Jacobi iteration are proved. And the numerical example indicates that the new scheme has the same parallelism and a higher rate of convergence than the Jacobi iteration.     

温度对平晶平面度影响的定性分析及相关问题探讨

在测量平晶工作面的平面度时，温度不仅对平晶平面度的大小有影响，而且直接影响对平晶表面形状（凹凸）的判断。文章给出了温度对平晶平面度影响的实例分析，并提出了两种平晶表面形状判断的辅助方法，且对JJG28—2000《平晶》检定规程中平晶表面形状判断方法进行了必要的补充说明。     

Transforming generate-and-test programs to execute under committed-choice AND-parallelism

This paper concerns the exploitation of user transparent inherent parallelism of pure Prolog programs using program transformation. We describe a novel paradigmenumerate-and-filter for transforming generate-and-test programs for execution under the committed-choice model extended to incorporate multiple solutions based on set enumeration. The paradigm simulates OR-parallelism by stream AND-parallelism integrating OR-parallelism, AND-parallelism, and stream parallelism. Generate-and-test programs are classified into three categories:simple generate-and-test, recursively embedded generate-and-test, and deeply intertwined generate-and-test. The intermediate programs are further transformed to reduce structure copying and metacalls. Algorithms are presented and demonstrated by transforming the representative examples of different classes of generate-and-test programs to Flat Concurrent Prolog equivalents. Statistics show that the techniques are efficient.Funded in part by Cleveland Advanced Manufacturing Program through the State of Ohio as a part of its core research program grant to Center of Automation and Intelligent Systems Research, Case Western Reserve University and NSF equipment grant CDA-8820390 to Kent State University.