Revisiting the cluster-based paradigm for implicit search result diversification     

Hai-Tao Yu  Adam Jatowt  Roi Blanco  Hideo Joho  Joemon M. Jose  Long Chen  Fajie Yuan 《Information processing & management》2018,54(4):507-528

To cope with ambiguous and/or underspecified queries, search result diversification (SRD) is a key technique that has attracted a lot of attention. This paper focuses on implicit SRD, where the subtopics underlying a query are unknown. Many existing methods appeal to the greedy strategy for generating diversified results. A common practice is using a heuristic criterion for making the locally optimal choice at each round. As a result, it is difficult to know whether the failures are caused by the optimization criterion or the setting of parameters. Different from previous studies, we formulate implicit SRD as a process of selecting and ranking k exemplar documents through integer linear programming (ILP). The key idea is that: for a specific query, we expect to maximize the overall relevance of the k exemplar documents. Meanwhile, we wish to maximize the representativeness of the selected exemplar documents with respect to the non-selected documents. Intuitively, if the selected exemplar documents concisely represent the entire set of documents, the novelty and diversity will naturally arise. Moreover, we propose two approaches ILP4ID (Integer Linear Programming for Implicit SRD) and AP4ID (Affinity Propagation for Implicit SRD) for solving the proposed formulation of implicit SRD. In particular, ILP4ID appeals to the strategy of bound-and-branch and is able to obtain the optimal solution. AP4ID being an approximate method transforms the target problem as a maximum-a-posteriori inference problem, and the message passing algorithm is adopted to find the solution. Furthermore, we investigate the differences and connections between the proposed models and prior models by casting them as different variants of the cluster-based paradigm for implicit SRD. To validate the effectiveness and efficiency of the proposed approaches, we conduct a series of experiments on four benchmark TREC diversity collections. The experimental results demonstrate that: (1) The proposed methods, especially ILP4ID, can achieve substantially improved performance over the state-of-the-art unsupervised methods for implicit SRD. (2) The initial runs, the number of input documents, query types, the ways of computing document similarity, the pre-defined cluster number and the optimization algorithm significantly affect the performance of diversification models. Careful examinations of these factors are highly recommended in the development of implicit SRD methods. Based on the in-depth study of different types of methods for implicit SRD, we provide additional insight into the cluster-based paradigm for implicit SRD. In particular, how the methods relying on greedy strategies impact the performance of implicit SRD, and how a particular diversification model should be fine-tuned.  相似文献   

药用、食用、观赏用百合组培快繁研究进展   总被引：2，自引：0，他引：2  

阮瑶瑶  丁健  杨懋勋 《深圳职业技术学院学报》2011,10(1):71-75

百合是商品价值很高的植物品种,有药用、食用、观赏等用途．应用植物种苗组织培养快速繁殖技术,可在短期内生产大量优质的百合种苗．现阶段国内广泛开展了对百合的组织培养和植株再生途径的研究,百合的组织培养研究已较为成熟,多种外植体都可诱导分化出植株．本文从外植体和基本培养基的选择、激素对初代、增殖及生根培养的影响、组培苗移栽等方面,综述了近年来国内的药用、食用、观赏用百合组培快繁研究的现状．  相似文献   

试论图书馆应对新的信息网络传播权保护法律环境挑战的对策     

王国丽 《现代情报》2007,27(4):27-29

《信息网络传播权保护条例》的颁布实施为图书馆的数字化信息服务带来了新的机遇和挑战,为此要从思想认识、队伍培塑、制度构建、行为规范、风险化解、技术实践、用户管理、参与立法等多方面采取综合应对措施。  相似文献   

网络文化传播对高校图书馆信息服务的冲击分析   总被引：1，自引：1，他引：1  

张永军 《现代情报》2006,26(5):63-65

首先阐述了网络文化传播的内涵和基本特点，以及对高校图书馆信息服务的冲击所造成较大负面影响的几种网络文化形式。接着论述了高校网络文化对大学生健康成长的影响和网络文化传播对高校图书馆信息服务冲击的反思与对策。以期望对高校图书馆的信息服务工作有所启示。  相似文献   

网络蠕虫预警与隔离控制方法研究     

于忠  于会 《科技通报》2006,22(4):544-548

针对网络蠕虫的快速传播特性,运用简单流行病学模型和从监控系统获得的非法扫描数据,通过检测非法扫描流量的增长趋势,在蠕虫病毒爆发初期对其进行实时预警,运用数据挖掘技术从扫描数据中自动获取扫描特征,据此特征对蠕虫扫描进行过滤和隔离,阻断蠕虫病毒的传播。  相似文献   

突发事件网络舆情传播的实证研究     

孙瑞英  王旭 《现代情报》2016,36(12):65

[目的/意义] 探索突发事件舆情传播网络的拓扑结构和传播规律、识别与评判突发事件舆情传播网络中重要节点,有助于从源头上控制舆情,增强公众、政府和媒体引导突发事件网络舆情的能力。[方法/过程] 以“魏则西事件”为实证研究对象、采集并整理数据,基于社会网络分析理论,运用Ucinet软件构建互动关系矩阵模型和Netdraw软件绘制该事件舆情传播网络社群图,从整体、局部和个体3个视角进行了该舆情传播网络结构测度分析。[结果/结论] 拓展了SNA的应用,从本质上揭示了突发事件网络舆情传播的结构特征与演变规律,总结并提出针对其本身拓扑结构的控制建议,最后,为从源头上弱化其不可控性,分别提出了公众、政府和媒体突发事件网络舆情传播的引导建议。  相似文献   

Deadzone compensation based on constrained RBF neural network     

Chiung-Hsin Tsai  Han-Tung Chuang 《Journal of The Franklin Institute》2004,341(4):361-374

In this paper, a modified adaptive neural network for the compensation of deadzone is described, and simulated on a hydraulic positioning system, in which the dynamic model is separated into a series of connection of a nonlinear (deadzone) subsystem and a linear plant. The proposed approach uses two neural networks. One is the radial basis function (RBF) neural network, which is used for identifying parameters of deadzone. Based on the penalty function used in optimization theory, a multi-objective cost function with constraint is adopted to provide the best deadzone approximation. The result is used to train the other neural network for the inverse compensation of deadzone. The RBF neural network also generates the parameters of the linear plant for the design of an adaptive controller. A convergence analysis for the network training process is also presented.  相似文献   

三种结缕草试管繁殖研究     

柴明良  胡叔良 《科技通报》1993,9(6):411-415

以结缕草属的马尼拉草、结缕草和中华结缕草进行了试管繁殖的研究.以马尼拉草匍匐茎为外植体,通过芽直接增殖和愈伤组织分化途径形成了2个试管无性系;从结缕草和中华结缕草的实生苗中也筛选出了若干个试管无性系.嫩极丛在1/2MS培养基添加IBA或 NAA0.5 mg/L、IBA0.25mg/L+NAAO.25mg/L上生根,经38 d培养,马尼拉草生根率为100％,结缕草为88％～90％.移栽成活率马尼拉草在95％以上,结缕草高于90％.试管草移栽后生长旺盛。  相似文献   

基于翡翠的传播话黄龙玉的研究和开发     

王文景 《保山师专学报》2011,30(5):105-108

翡翠传播的历史就是翡翠从鲜为人知到广为接受再到辉煌、鼎盛的发展之路,而当今黄龙玉的兴盛和发展就是在重复翡翠已经走过的路。黄龙玉部分取代翡翠,成为玉器市场的新宠,是我国现阶段玉石（器）行业发展的一个新趋势。  相似文献   

谈企业ERP系统选型     

王曼 《河南职业技术师范学院学报(职业教育版)》2011,(9)

由于实施ERP项目效果方面的巨大诱惑,我国企业争相引入ERP系统,但由于选型前的准备不足或选型时的考虑不周等原因使得很多企业实施ERP项目遭遇失败。根据企业自身特点选择适合自己需要的ERP软件,是ERP项目成功实施的关键因素。因此,如何选型是成功的关键也即是文章阐述的重点。  相似文献