Analyzing imbalance among homogeneous index servers in a web search system

The performance of parallel query processing in a cluster of index servers is crucial for modern web search systems. In such a scenario, the response time basically depends on the execution time of the slowest server to generate a partial ranked answer. Previous approaches investigate performance issues in this context using simulation, analytical modeling, experimentation, or a combination of them. Nevertheless, these approaches simply assume balanced execution times among homogeneous servers (by uniformly distributing the document collection among them, for instance)—a scenario that we did not observe in our experimentation. On the contrary, we found that even with a balanced distribution of the document collection among index servers, correlations between the frequency of a term in the query log and the size of its corresponding inverted list lead to imbalances in query execution times at these same servers, because these correlations affect disk caching behavior. Further, the relative sizes of the main memory at each server (with regard to disk space usage) and the number of servers participating in the parallel query processing also affect imbalance of local query execution times. These are relevant findings that have not been reported before and that, we understand, are of interest to the research community.     

Extending WHIRL with background knowledge for improved text classification

Intelligent use of the many diverse forms of data available on the Internet requires new tools for managing and manipulating heterogeneous forms of information. This paper uses WHIRL, an extension of relational databases that can manipulate textual data using statistical similarity measures developed by the information retrieval community. We show that although WHIRL is designed for more general similarity-based reasoning tasks, it is competitive with mature systems designed explicitly for inductive classification. In particular, WHIRL is well suited for combining different sources of knowledge in the classification process. We show on a diverse set of tasks that the use of appropriate sets of unlabeled background knowledge often decreases error rates, particularly if the number of examples or the size of the strings in the training set is small. This is especially useful when labeling text is a labor-intensive job and when there is a large amount of information available about a particular problem on the World Wide Web.

Phonological processing and emergent literacy in younger and older preschool children

Phonological awareness, phonological memory, and phonological access to lexical storage play important roles in acquiring literacy. We examined the convergent, discriminant, and predictive validity of these phonological processing abilities (PPA) in 389 3-, 4-, and 5-year-old children. Confirmatory factor analysis supported the validity of each PPA as separate from general cognitive ability and separate from each other. Multigroup structural equation modeling (SEM) with mean structure demonstrated that older preschoolers have better developed latent PPA than younger preschoolers but that the structure of PPA is equivalent. RAN was found uniquely associated with letter knowledge and text discrimination in younger preschoolers, and PA was found uniquely associated with word reading skills in older preschoolers. Finally, general cognitive ability was only indirectly associated with emergent literacy via PPA. These results highlight the importance of PPA in the early literacy development of English-speaking preschool children.     

使用善锋软件审核加工参考文献的几点思考

善锋软件是编辑审核参考文献的有效工具。本文总结了善锋软件的诸多实用功能:定制参考文献著录内容和著录格式,标记出新、旧参考文献的所有差异并协助编辑纠正各类文字性和格式性差错,提供参考文献原文链接,对参考文献的遗漏、颠倒、重复等问题进行校验,对文内、文后参考文献责任者姓名与序号(出版年份)一致性进行检验等。来源数据的先天质量问题可能导致善锋软件输出结果出现对应的细节性偏差。使用善锋软件时,只要严格执行使用流程,对软件标记出的疑似差错进行原文核查,就可以消除参考文献中的各类差错。     

“序换”格续貂

根据谭永祥先生1983年首创的序换辞格论述,结合近期的语言材料,用吴士文辞格结构理论,对序换格进行了分析研究。以语法单位为标准划分出序换格的类别,并归纳出序换格的修辞作用,从而进一步认识这个比较常见常用的修辞手段。     

教务管理中多数据表交叉处理技术探讨

学校的教务管理过程中,经常会涉及到多张数据表之间的数据分析与处理,而且这些表的数据类型也不尽相同。通过Excel的VLOOKUP、ISERROR、IF等多个函数的综合运用、VFP查询操作、数据表格类型转换等方面实现对多数据表的交叉处理。     

过程装备与控制工程专业实验室管理系统开发

按照综合性、设计性实验的要求,把过程装备与控制工程专业实验室建设管理与实验内容等融合到实验室管理系统中,完善和创新了该专业实验管理方法;介绍了利用雅奇MIS编制实验室管理系统的详细方法和过程,在实验室管理系统信息化后的实验室环境中,学生既可以直接学习传统实验、实践的操作,还可以获得实验室中其它实验设备、仪器的操作使用方法;实验室管理上减轻了实验教师的工作量,提高了实验室的利用率和开放性及学生做实验的积极性,促进优良学风养成;同时为教师提供了良好的实验教学研究环境,为更好地培养学生的实践能力和创新精神,培养高素质的应用型人才打下基础。     

高职科研在专业建设中的作用

以广东轻工职业技术学院高分子材料加工技术专业为例,分析了高职院校开展科研工作在专业建设中所起的作用。科研对于专业的可持续发展,师资水平的提高以及专业对外服务能力的提升起到重要推动作用。同时,也分析了目前高职院校开展科研工作的不利因素。     

谈周朴园权势意识的凸现

《雷雨》是现代文学的经典之作,它含蓄的语言和丰富的潜台词是文坛上永不褪色的华彩。以周朴园的语言为分析对象,从语量和语势两角度,探析周朴园的权势意识的凸现手段,体会曹禺的语言艺术魅力。     

基于谱减的双元指向传声器阵列语音增强

设计了一种结构简单的用于语音增强的双元指向性传声器阵列,利用阵列中不同方位阵元对目标信号和干扰信号的增益不同的特点,有效估计噪声信号的功率谱,再利用传统谱减算法的思想,实现语音增强。实验结果表明提出的算法是有效的,与经典的谱减算法相比具有更佳的语音增强效果。