Parsimonious translation models for information retrieval     

Seung-Hoon Na  In-Su KangJong-Hyeok Lee 《Information processing & management》2007

In the KL divergence framework, the extended language modeling approach has a critical problem of estimating a query model, which is the probabilistic model that encodes the user’s information need. For query expansion in initial retrieval, the translation model had been proposed to involve term co-occurrence statistics. However, the translation model was difficult to apply, because the term co-occurrence statistics must be constructed in the offline time. Especially in a large collection, constructing such a large matrix of term co-occurrences statistics prohibitively increases time and space complexity. In addition, reliable retrieval performance cannot be guaranteed because the translation model may comprise noisy non-topical terms in documents. To resolve these problems, this paper investigates an effective method to construct co-occurrence statistics and eliminate noisy terms by employing a parsimonious translation model. The parsimonious translation model is a compact version of a translation model that can reduce the number of terms containing non-zero probabilities by eliminating non-topical terms in documents. Through experimentation on seven different test collections, we show that the query model estimated from the parsimonious translation model significantly outperforms not only the baseline language modeling, but also the non-parsimonious models.  相似文献   

An empirical study of query expansion and cluster-based retrieval in language modeling approach     

Seung-Hoon Na  In-Su Kang  Ji-Eun Roh  Jong-Hyeok Lee 《Information processing & management》2007

The term mismatch problem in information retrieval is a critical problem, and several techniques have been developed, such as query expansion, cluster-based retrieval and dimensionality reduction to resolve this issue. Of these techniques, this paper performs an empirical study on query expansion and cluster-based retrieval. We examine the effect of using parsimony in query expansion and the effect of clustering algorithms in cluster-based retrieval. In addition, query expansion and cluster-based retrieval are compared, and their combinations are evaluated in terms of retrieval performance by performing experimentations on seven test collections of NTCIR and TREC.  相似文献   

重大突发公共卫生事件下公众信息获取行为与错失焦虑研究——以新型冠状病毒肺炎疫情为例     

耿瑞利  徐建国  金燕  王娜  付立宏 《图书情报工作》2020,64(15):112-122

[目的/意义] 新型冠状病毒肺炎（COVID-19）暴发流行后,大量信息和舆论铺天盖地而来。准确把握疫情暴发期公众的信息获取行为及特征,分析探索错失焦虑的形成与影响因素,对于重大突发公共卫生事件的应急管理与科学决策具有重要价值。[方法/过程] 基于使用与满足理论、认知心理学等梳理分析错失焦虑、信息获取行为、无聊倾向及情绪之间的关系,构建研究模型。通过问卷调查法采集957份样本数据,利用偏最小二乘法检验模型,结合访谈对结果进行讨论分析。[结果/结论] 重大突发公共卫生事件暴发期,移动新媒体是信息获取的主要渠道,接收推送分享与主动搜寻行为均衡,信息阅读观看的日均耗费时间较长,呈现高频次短时间隔获取特征。疫情关注度显著正向影响错失焦虑与信息获取行为;无聊倾向与错失焦虑之间呈现显著正相关关系。错失焦虑是信息获取的动机性因素,具有显著正向影响作用;错失焦虑较高的个体更容易感染负面情绪;信息获取行为与负面情绪之间有显著正相关关系。  相似文献   

民国济南公路史小考     

刘娜 《兰台世界》2020,(1):140-144

20世纪30年代之前,山东政局动荡,公路建设虽有规划但难以实施,公共交通事业也仍以马车、人力车及自行车为主。韩复榘主鲁后,对全省公路颇有建设,并借华北运动会在济召开之机,修缮济南市内公路。龙洞与灵岩寺是济南近郊的两处名胜,抗战前山东建设厅多方筹款修通了济南市至龙洞和灵岩寺的汽车路并开通了游览专线。至20世纪30年代中期,济南至全省各地的长途运输事业也有了长足发展,促进了山东经济格局及社会的变迁。  相似文献   

迈克尔·富兰教育变革思想述评     

王娜 《现代教育科学》2011,(1)

加拿大学者迈克尔·富兰多年从事教育变革的理论和实践研究,著有大量关于教育变革思想方面的书籍,并就为什么需要变革、需要怎样的变革、怎样变革以及怎样变革更有效等问题进行了系统的研究.本文分为迈克尔·富兰教育变革思想产生的背景、主要内容以及对当今中国基础教育课程改革的启示三个部分,意图对迈克尔·富兰教育变革思想及其现实意义进行述评.  相似文献   

知识的智慧化、智慧的场景化、智能的泛在化——探索智慧知识服务的逻辑框架     

张晓林  梁娜 《中国图书馆学报》2023,49(3):4-18

数字化转型+AI环境下,我们正处于知识生态环境和知识技术体系的交汇重塑中,对知识、智慧和智能基础设施的认识很大程度上将决定我们的生存方式和生存几率。知识对象已内在地结构化、语义化、可定制、可关联,已涵盖从内容对象到知识关系网络到知识创造与利用流程,成为可交互、可计算的智能体。在智慧化的各类知识对象支持下,通过场景驱动的创新机制,可在用户解决问题的过程中,通过数据、模型、计算和交互来支持感知智能、认知智能和决策智能。通过泛在智能机制(智联网),利用边缘智能、智能集成感知体、智慧知识内容对象、智慧化业务流程与管理机制等,可积极推动智慧知识对象生态体系的构建与管理、知识与数据双驱动的问题分析与决策推理、多源资源环境下AI赋能的个性化知识服务的动态构建,以有效推动智慧知识服务的普惠可及。为实现上述愿景,重要的是运用第一性原理思维,推动新形势下的服务逻辑和业务机制的范式转变。图2。参考文献67。  相似文献   

静态箱法在甲烷排放及稻田甲烷减排策略研究中的应用   总被引：1，自引：0，他引：1  

王维奇  雷波  李鹏飞  赵娜  林德华 《实验技术与管理》2011,28(7):53-56,78

为揭示天然湿地与稻田甲烷排放特征的差异,采用静态箱法对闽江河口天然湿地和稻田甲烷排放特征进行了比较,并探讨了水旱轮作的甲烷减排模式。结果表明:早稻田平均甲烷排放量为17.03 mg/m2.h,高于相应季节的天然芦苇沼泽甲烷排放量(7.47 mg/m2.h);天然湿地和稻田土壤理化特征差异是导致甲烷排放量不同的主要原因;早稻田甲烷排放量日变化主要受温度影响,而潮汐是影响天然芦苇沼泽的关键因素;水旱轮作可有效降低稻田甲烷排放。  相似文献   

Experimental performance of moderate and high temperature heat pump charged with refrigerant mixture BY-3     

陈成敏  张于峰  邓娜  马洪亭  张彦所  马丽筠  胡晓微 《天津大学学报(英文版)》2011,17(5):386-390

Theoretical and experimental analysis of a new refrigerant mixture BY-3 was conducted based on a single-stage vapor compression refrigeration system. The water-water heat pump system used BY-3 to produce hot water when the low temperature was 20 ℃. The following results were obtained: the highest temperature at the condenser outlet reached about 85 ℃; when the difference between the water temperatures at the condenser outlet and the evaporator inlet was less than 40 ℃, the coefficient of performance (COP) was larger than 4; when the difference reached 55 ℃, the COP still kept 3; the discharge temperature of BY-3 was lower than 100 ℃, and the refrigerant vapor pressure kept lower than 1.8 MPa. When the water temperature at the condenser outlet reached over 85 ℃, nearly a 5 ℃ superheating temperature was maintained.  相似文献   

应用型人才培养的地方本科院校化学实验教学改革     

彭娜  李红山  彭梦侠  王开峰  林穗云 《实验室研究与探索》2011,(8)

从应用型本科人才培养目标出发,针对当前地方本科院校化学实验教学存在的问题,在实验课程体系、实验教学内容、实验教学模式及实践教学等方面进行了改革。  相似文献   

网络多媒体辅助下大学英语听力课程语料库的建设     

胡娜 《沙洋师范高等专科学校学报》2011,12(2):42-43,47

文章首先从国内外大学英语听力课程的教学理论出发,结合大学英语课程的教学需要和实际教学情况,分析了在新的网络多媒体环境下建设新的听力课程语料库的必要性。其次,以语料库的理论和方法为理论前提,结合目前大学英语听力课程的实际教学情况,探讨了从英语听力资源库的构成和应用等方面建立语料库的方法。  相似文献