Query expansion with terms selected using lexical cohesion analysis of documents     

Olga Vechtomova  Murat Karamuftuoglu 《Information processing & management》2007

We present new methods of query expansion using terms that form lexical cohesive links between the contexts of distinct query terms in documents (i.e., words surrounding the query terms in text). The link-forming terms (link-terms) and short snippets of text surrounding them are evaluated in both interactive and automatic query expansion (QE). We explore the effectiveness of snippets in providing context in interactive query expansion, compare query expansion from snippets vs. whole documents, and query expansion following snippet selection vs. full document relevance judgements. The evaluation, conducted on the HARD track data of TREC 2005, suggests that there are considerable advantages in using link-terms and their surrounding short text snippets in QE compared to terms selected from full-texts of documents.  相似文献   

Efficient implementation of associative classifiers for document classification     

Yongwook Yoon  Gary Geunbae Lee 《Information processing & management》2007

In practical text classification tasks, the ability to interpret the classification result is as important as the ability to classify exactly. Associative classifiers have many favorable characteristics such as rapid training, good classification accuracy, and excellent interpretation. However, associative classifiers also have some obstacles to overcome when they are applied in the area of text classification. The target text collection generally has a very high dimension, thus the training process might take a very long time. We propose a feature selection based on the mutual information between the word and class variables to reduce the space dimension of the associative classifiers. In addition, the training process of the associative classifier produces a huge amount of classification rules, which makes the prediction with a new document ineffective. We resolve this by introducing a new efficient method for storing and pruning classification rules. This method can also be used when predicting a test document. Experimental results using the 20-newsgroups dataset show many benefits of the associative classification in both training and predicting when applied to a real world problem.  相似文献   

收益管理的战略扩展与系统升级——基于中国民航的分析     

谢泗薪  陈鸣  都业富 《软科学》2005,19(4):52-55

论述了收益管理对我国航空公司的重要性和必要性。追随收益管理的演进历程,探讨了收益管理的产生、发展及其战略内涵和系统架构。运用定性和定量方法对我国航空公司收益管理进行系统评价与分析,对升级收益管理系统提出了自己的建议:我国航空公司只有让员工满意和员工忠诚,才能最终获得顾客满意和顾客忠诚,真正实现收益的长远化与最大化。  相似文献   

SDQE: towards automatic semantic query optimization in P2P systems     

Xing Zhu  Hualiang Cao  Yong Yu 《Information processing & management》2006

Conventional information retrieval technology (i.e. VSM) faces many difficulties when being implemented in complex P2P systems for the lack of global statistic information (e.g. IDF) and central services. In this paper, we suggest a novel query optimization scheme (Semantic Dual Query Expansion, SDQE) that makes full use of the context information supplied by the local document collection. Latent Semantic Indexing (LSI) is used to explore the local context information. By comparing the different local context information hidden in different document collections, it is possible to solve the synonymy–polysemy problem in VSM. The experiments prove that our scheme is effective to improve the retrieval performance in P2P systems without knowing the global statistic information.  相似文献   

Two direct Tustin discretization methods for fractional-order differentiator/integrator   总被引：1，自引：0，他引：1  

Blas M. Vinagre  Ivo Petráš 《Journal of The Franklin Institute》2003,340(5):349-362

This paper deals with fractional calculus and its approximate discretization. Two direct discretization methods useful in control and digital filtering are presented for discretizing the fractional-order differentiator or integrator. Detailed mathematical formulae and tables are given. An illustrative example is presented to show the practically usefulness of the two proposed discretization schemes. Comparative remarks between the two methods are also given.  相似文献   

乡村人口收缩背景下经济发达地区村庄用地演变：以江苏省常熟市为例     

田秀琴  高金龙  陈雯  陈江龙 《中国科学院大学学报》2018,35(5):645-653

在乡村人口收缩背景下,部分地区村庄用地规模持续增长。为研究这一现象,以经济发达的江苏省常熟市为例,基于2009-2013年土地利用变更调查数据,结合多时相高清卫星影像识别村庄用地类型,阐释村庄用地的演变特征,并从土地供需角度探究村庄用地持续扩张的机制。将村庄用地划分为村庄商服住宅用地、村庄工业用地和其他村庄用地3类。分析结果表明：1）2009-2013年,常熟市村庄工业用地净增量占比53.92%,是乡村空间扩展的主要原因,商服住宅用地净增量占17.88%,且以住宅用地的增长为主;2）常熟市村庄住宅用地持续增长主要源于地方政府对农村社区建设用地补偿过量,村庄工业用地的快速扩张则主要源于乡村工业化的持续推进、企业生产利益追逐及地方政府对财税和经济增长的追求。乡村价值回归提升趋势下,人口收缩的乡村发展转型和土地节约集约利用势在必行。乡村生活空间合理集中化、生产空间进一步集约化、保留和改善生态空间,从而实现乡村“三生一体”。  相似文献   

2002-2012年达累斯萨拉姆城市蔓延特征及影响因素     

张家旗  陈爽  Damas W. Mapunda 《中国科学院大学学报》2018,35(5):663-673

以坦桑尼亚首位城市达累斯萨拉姆2002、2007和2012年土地利用分类数据为基础,结合实地调研,运用扇形分析和同心圆分析等方法,以及用地增长弹性系数、扩展强度指数、紧凑度、分形维数等指标,研究达累斯萨拉姆近年来城市蔓延的总体态势和空间格局特征。研究结果表明：1）2002-2012年间达累斯萨拉姆城市蔓延特征明显,蔓延程度较高,蔓延速度不断加快,主要表现为非正式聚落不断增长情况下的城乡混合发展,侵占的土地类型主要为裸地,其次为植被;2）2002-2007年城市建成区主要沿交通干道以及在市中心周边进行轴线式蔓延,2007-2012年主要在交通干道间及城市边缘地区进行填充式蔓延,城市空间形态由指状向团块状演变;3）城市蔓延方向性明显,向西北、西、西南和东南扩展较多,东南方向成为新的扩展热点,且表现出明显的距离衰减特征;4）城市蔓延主要受到人口与经济增长、交通条件改善、政策变化及土地制度缺陷等因素的影响,其中交通设施起到重要的空间引导作用。  相似文献   

高校中体育拓展俱乐部的建立及其运作模式     

韩莎莎 《湖北体育科技》2011,30(2):242-244

高校体育教学课堂的延伸可以采取建立体育俱乐部的方式,这也是高校体育教学逐步实现现代化的一种体现,是一种可采用的人性化的教学模式,可以很好的丰富目前高校体育教学的趣味性和创新性.高校中建立体育拓展俱乐部还能够为体育拓展运动的发展提供一个广阔的平台.  相似文献   

运城学院体育教育专业开设拓展训练课程的必要性分析     

赵亚英 《搏击·武术科学》2011,(9):65-67

文章通过对运城学院体育系部分学生进行调查,对体育教育专业开设拓展训练课程的必要性进行分析,结果表明,体育系多数学生认为开展拓展训练课很有必要,不仅能增强其整体能力,而且其社会适应能力也会得到发展和提高。  相似文献   

基于查询意图聚类的实时搜索建议     

周之诚 《现代图书情报技术》2011,27(2):87-93

对于搜索引擎返回的结果太多且较少考虑用户个性差异等缺陷,提出根据用户查询意图,实时给予多个主题的搜索建议,帮助用户更准确地描述所需信息,修正查询词与真实意图之间的差距,提高检索效率。同时运用K-means算法,对资源类别的意图特征值相似用户进行聚类,缩小查找目标对象最近邻居的范围,提高搜索建议的实时响应速度。实验结果表明,该方法是可行的。  相似文献