面向高通量计算机的图算法优化技术

随着互联网技术的蓬勃发展,图数据的规模呈爆炸式增长.如何高效地处理大规模图数据逐渐成为工业界和学术界关注的焦点.宽度优先搜索算法是解决图遍历问题的经典算法,也是Graph500基准的核心测试程序之一.高通量计算机采用ARM架构的众核体系结构,具有高并发、强实时、低功耗等适于大数据计算的特点.在单节点上,BFS算法的优化已取得一系列进展,首先对现有的优化技术进行系统的介绍,并在此基础上提出2种面向高通量计算机的优化手段,通过减少冗余访存和提高缓存局部性,有效提高了算法的访存效率.通过这些优化手段,在高通量计算机上对BFS算法的性能进行了系统的评估.对于顶点规模为230的Kronecker图(顶点数为230,边数为234),优化后的BFS算法在高通量计算机上的平均性能为24.26 GTEPS.与两路x86架构服务器相比,单节点具有1.18倍的性能优势.在性能功耗比方面,高通量计算机的结果为181.04 MTEPS/W.在2019年6月份的Green Graph500面向大数据集的排行榜上取得第2名的成绩.综上,高通量计算机的高并发和低功耗等特点非常适合处理大规模图计算等数据密集型应用.     

机床加工过程中的振动实验研究

分析了数控车床加工过程中切削颤振的产生机理,总结了目前国内外对切削颤振抑制理论和实践的研究现状.基于CJK6140数控车床利用脉冲激振法对刀架系统进行初步实验研究,并且提出了基于计算机仿真技术对加工过程进行动态仿真的方法,研究结果为提高加工效率提供了依据.     

一种等高线快速自动标定算法

首先讨论了使用图论方法表示等高线图和自动标定等高线的一般原理，然后，提出了一种快速实用的等高线高程自动标定算法。该算法的实质是设计了一种称做大区域的填充算法进行区域标定和快速生成等高线、区域自由树的方法以及在树搜索过程中冲突的检验。     

纳米粒子晶格畸变率的数量级研究

晶格畸变率是纳米粒子的一个重要参数。用X射线衍射积分宽度法确定了纳米CeO2粒子的晶格畸变率，研究了晶格畸变与晶粒度之间的关系，结合已有资料讨论了纳米粒子晶格畸变率的数量级大小。结果表明，不合理的计算方法可能导致计算出来的晶格畸变值严重失实。     

Efficient parallel algorithms for breadth first spanning forests of general graphs

Ghosh and Bhattacharjee propose [2] (Intern. J. Computer Math., 1984, Vol. 15, pp. 255-268) an algorithm of determining breadth first spanning trees for graphs, which requires that the input graphs contain some vertices, from which every other vertex in the input graph can be reached. These vertices are called starting vertices. The complexity of the GB algorithm is O(log² n) using O{n ³) processors. In this paper an algorithm, named BREADTH, also computing breadth first spanning trees, is proposed. The complexity is O(log² n) using O{n ³/logn) processors. Then an efficient parallel algorithm, named- BREADTHFOREST, is proposed, which generalizes algorithm BREADTH. The output of applying BREADTHFOREST to a general graph, which may not contain any starting vertices, is a breadth first spanning forest of the input graph. The complexity of BREADTHFOREST is the same as BREADTH.     

Non-linear analysis of steel-concrete composite frames with full and partial shear connection subjected to seismic loads

The seismic performance of moment-resisting frames consisting of steel-concrete composite beams with full and partial shear connection is investigated. To this end, six full scale composite substructures with headed stud shear connectors have been tested and the corresponding inelastic response to both monotonic and variable reversed displacements have been investigated. Three-dimensional finite element models of the substructures set with the ABAQUS code and based on shell elements are established in order to evaluate different modelling assumptions and local effects; and to calibrate a one-dimensional model conceived with the Drain-3DX code relying on layered beam-column elements. The one-dimensional model is then exploited for a parametric study on two four-storey frames by means of non-linear dynamic analyses. The analyses have revealed that composite frames with a low shear connection degree of about 0.4 perform as well as their companion frames with full shear connection under severe seismic loads. Nonetheless, the shear connection degree should be high enough in order to protect shear connectors in the central part of beams from failure. Although their equivalent damping is not very high, shear connectors could reduce the ductility demand on other parts of a composite frame, such as beam ends or partial strength beam-to-column joints. This design option could provide a further means to achieve a favourable performance of a composite moment-resisting frame, in addition to the benefit of cost reduction.     

基于子树广度的Web信息抽取

提出一种新的网页信息抽取方法,基于子树的广度可不加区分地对不同科技文献网站的页面信息进行自动抽取。对大量科技文献网站进行信息抽取实验,已应用到甘肃省科技文献共享平台。实验结果证明,该方法能不依赖科技文献网页的来源而自动地抽取相关信息,并能保证较高的数据抽取回召率和查准率。     

轮毂多盘式无铁心永磁同步电机永磁体结构优化

将不等厚排列技术与90°Halbach阵列以及不等宽排列技术相结合应用到两个外转子磁钢分析,中间盘采用普通磁钢排列,通过改变磁钢排列的厚度及宽度,来进一步提高多盘式无铁心永磁同步电机气隙磁密的基波幅值和波形的正弦性,从而提高电机性能。对16极盘式永磁同步电机进行仿真建模,将"不等宽排列技术+90°Halbach阵列"模型以及其优化模型"不等厚排列技术+90°Halbach阵列+不等宽排列技术"进行静态气隙磁场对比分析。仿真数据表明,"不等厚排列技术+90°Halbach阵列+不等宽排列技术"使得周向磁密波形和切向磁密波形都大为改善,磁场波形更接近于正弦分布特征,其中周向磁密波形畸变率改善了67.02%,气隙周向磁密幅值提高了8.15%。     

软管用8011铝合金箔材生产工艺研究

采用SEM表面形貌和元素定量分析方法对铝箔针孔形成机理进行了研究，提出了“非金属夹渣在轧制过程中的脆性断裂可导致铝箔形成短程线性针孔”，以及“铸轧带材表面缺陷也可形成分散性针孔”的机理；将这一机理应用到软管用铝合金箔材(简称软管箔)的生产实践中，在减少针孔方面取得了重大突破。介绍了宽幅、超薄软管箔的生产技术和性能要求。     

一种基于Web数据库的动态表头的实现

针对目前流行的C/S三层结构和动态网页技术 ,提出一种基于Web数据库的动态表头的生成方法。该方法充分分析了在HTML页面中表头的特点 ,利用树结构及广度优先遍历算法 ,实现复杂表头的定制 ,并在WindowsNTServer及IE4.0环境下对该方法予以编程实现。该方法不仅克服了静态生成表头的不足 ,而且还增强了应用系统的灵活性 ,适应性和应变能力 ,能较好地满足用户不断发展的需求。