Incrementally building frequent closed itemset lattice

A concept lattice is an ordered structure between concepts. It is particularly effective in mining association rules. However, a concept lattice is not efficient for large databases because the lattice size increases with the number of transactions. Finding an efficient strategy for dynamically updating the lattice is an important issue for real-world applications, where new transactions are constantly inserted into databases. To build an efficient storage structure for mining association rules, this study proposes a method for building the initial frequent closed itemset lattice from the original database. The lattice is updated when new transactions are inserted. The number of database rescans over the entire database is reduced in the maintenance process. The proposed algorithm is compared with building a lattice in batch mode to demonstrate the effectiveness of the proposed algorithm.     

数据仓库技术在高校招生工作中的应用研究

以四川交通职业技术学院为例,讨论如何建立数据仓库,通过SQL Server Integration Service将招生数据经过清洗、转换加载到数据仓库,建立以招生为主题的多维数据集,使用OLAP工具对招生数据进行分析,使用Excel将分析结果展现给决策者。     

基于Iceberg概念格的最大频繁项集挖掘

最大频繁项集挖掘算法存在扫描数据集次数多和候选集规模过大等局限。基于Iceberg概念格模型,提出一种在Iceberg概念格上挖掘最大频繁项集的算法ICMFIA。该算法通过一次扫描数据集构建Iceberg概念格,利用Iceberg概念格中频繁概念之间良好的覆盖关系能快速计算出最大频繁项集所对应的最大频繁概念,所有最大频繁概念的内涵就是所求的最大频繁项集的集合。实验结果表明,该算法具有扫描数据集次数少和挖掘效率高的优点。     

冰山理论下的《乞力马扎罗山上的雪》

海明威的创作具有＂冰山风格＂,《乞力马扎罗山上的雪》就是海明威笔下一篇浓缩了的长篇小说,是体现其冰山理论的代表作。小说中雪、豹子、秃鹫和鬣狗等意象各具意蕴,象征意义深刻,揭示了人物的性格特征,渲染了气氛,达到了深化主题的目的。作者通过对意识流叙事手法的运用,巧妙安排了主人公的意识在时间和空间里的自然流动,省去了大量的笔墨,有利于海明威＂冰山风格＂创作理论的运用。     

层次立方体(H-Cube)的自适应计算

多维数据立方（Cube）的计算对联机分析处理（online analytical processing，OLAP）有着极为重要的作用。针对传统的多维数据Cube计算中的不足，提出了自适应的计算方法，并给出了带有层次的Cube计算算法HCA算法。     

一种新柱式

文章介绍了在计算机的帮助下产生的一种全新的柱式。它基于一种基本的折叠手法,其结果所呈现的极其丰富的细节超越了传统cAD工具能够绘制的极限,也超越了肉眼所能观察的极限。这些出乎意料的形式与极其微小的细节来自计算机程序的反复迭代,它们超出了建筑师的经验、教育和历史认知,无论从手法还是结果来看,都是一种彻底的创新。文章还指出,建造如此复杂的细节需要现代化的数字加工技术与独特的加工技巧。     

An adjusted temperature wall function for turbulent forced convective heat transfer for bluff bodies in the atmospheric boundary layer

Accurate convective heat transfer predictions are required in building engineering and environmental studies on urban heat islands, building energy performance, building-envelope durability or conservation and (natural) ventilation of buildings. When applying computational fluid dynamics (CFD) for these computationally-expensive studies at high-Reynolds numbers, wall functions are mostly used to model the boundary-layer region. In this study, an adjustment to the standard temperature wall function is proposed for forced convective heat transfer at surfaces of typical wall-mounted bluff bodies in turbulent boundary layers, such as the atmospheric boundary layer, at moderate to high Reynolds numbers. The methodology to determine this customised temperature wall function (CWF) from validated numerical data of CFD simulations using low-Reynolds number modelling (LRNM) is explained, where a logarithmic- law behaviour is found. The performance of this CWF is evaluated for several bluff-body configurations. Standard wall functions (SWFs) yield deviations of about 40% for the convective heat transfer coefficient, compared to LRNM. With the CWF however, these deviations are reduced to about 10% or lower. The CWF therefore combines increased (wall-function) accuracy for convective heat transfer predictions with the typical advantage of wall functions compared to LRNM, being a lower grid resolution in the near-wall region, which increases computational economy and facilitates grid generation. Furthermore, this CWF can be easily implemented in existing CFD codes, and is implemented in the commercial CFD code Fluent in this study.     

国家游泳中心钢结构施工卸载过程及运营期间应变健康监测及计算模拟分析

空间结构施工卸载过程和运营状态受力是十分复杂的。本文在对100余种工况受力分析的基础上,依据应变传感器位置选择原则,首先设计国家游泳中心(简称"水立方")应变监测系统;其次,建立水立方施工卸载过程模拟的有限元模型和运营状态的有限元模型;采用应变监测系统和有限元模型分别监测和模拟水立方施工卸载过程关键杆件的应力变化,以及脚手架的应力变化全过程,分析关键杆件应变变化规律。在此基础上,对水立方运营阶段的温度变化及其产生的应变进行监测,并采用有限元模型进行温度变形计算。结果表明,监测期间,水立方其他荷载较小,温度是主要控制荷载,随温度升高,应变增加,最高温度达到75℃,最大温度应变变化接近500με。