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   

The Influence of Hygroscopic Materials on the Fluctuation of Relative Humidity in Museums Located in Historical Buildings     

C. Ferreira  V. P. de Freitas 《文物保护研究》2020,65(3):127-141

ABSTRACT

The preservation of artefacts in museum collections is profoundly affected by fluctuations in temperature and, especially, relative humidity (RH). Since the late nineteenth century, many studies have been carried out on the best way to control hygrothermal conditions. In old buildings located in maritime temperate climate zones (such as Portugal) with strong thermal inertia, and which have low ventilation rate (relative to the volume and number of visitors), daily and seasonal hygroscopic inertia may help to assure the maintenance of RH stabilization conditions. The use of expensive active systems may be minimized through the passive behaviour of internal finishing building materials. This work presents the results of an experimental laboratory study conducted in a flow chamber to demonstrate the enormous potential of hygroscopic materials in stabilizing interior relative humidity. Based in these results and in-situ monitoring in a museum housed in a building, located in Porto, with a typical construction of the 1950s (granite masonry and reinforced concrete slabs), a numerical analysis was done to quantify the influence of hygroscopic materials in stabilizing the interior relative humidity.  相似文献   

The load-velocity profile differs more between men and women than between individuals with different strength levels     

Alejandro Torrejón  Carlos Balsalobre-Fernández  G. Gregory Haff 《Sports biomechanics / International Society of Biomechanics in Sports》2019,18(3):245-255

This study aimed to determine the suitability of the load-velocity relationship to prescribe the relative load (%1RM) in women, as well as to compare the load-velocity profile between sexes and participants with different strength levels. The load-velocity relationship of 14 men (1RM: 1.17 ± 0.19) and 14 women (1RM: 0.66 ± 0.13) were evaluated in the bench press exercise. The main findings revealed that: (I) the load-velocity relationship was always strong and linear (R² range: 0.987–0.993), (II) a steeper load-velocity profile was observed in men compared to women (Effect size [ES]: 1.09), with men showing higher velocities for light loads (ES: ? 0.81 and ? 0.40 for the y-intercept and 30%1RM, respectively), but women reporting higher velocities for the heavy loads (ES: 1.14 and 1.50 at 90%1RM and 100%1RM, respectively); and (III) while the slope of the load-velocity profile was moderately steeper for weak men compared to their strong counterpart (ES: 1.02), small differences were observed between strong and weak women (ES: ? 0.39). While these results support the use of the individual load-velocity relationship to prescribe the %1RM in the bench press exercise for women, they also highlight the large disparities in their load-velocity profile compared to men.  相似文献   

基于熵权-TOPSIS模型的大风浪条件下引航员登船水域选址     

周宁  范中洲  赵羿 《上海海事大学学报》2020,41(1):46-50

为保障大风浪条件下引航员登船安全、周边船和被引船的安全以及港口的安全高效运营,选取合理的引航员登船水域至关重要。综合考虑熵权法和TOPSIS法的优点,基于熵权-TOPSIS模型对大风浪条件下引航员登船水域进行优选研究。以大风浪条件下广州港引航员登船水域选址为例,运用该模型对3个备选方案进行评价,求得方案2的相对贴近度最大。该方案所述的引航员登船水域为大风浪条件下最优登船水域,且与实际选址一致。经实例验证,该模型较为可靠,实用性强。  相似文献   

普通高校化学专业大学物理教学内容改革的几点建议   总被引：1，自引：0，他引：1  

向荣 《巢湖学院学报》2011,13(3):146-148

改变《大学物理》在普通高校化学专业的教授内容范围。利用有限课时增加与化学直接相关的内容如热学、量子初步等。减少其他如电磁、光学内容。可以增加学生学习兴趣、增大课堂内容含量。  相似文献   

相对运动与参考系的选择     

田旭东  张学权 《铜仁学院学报》2003,5(Z1):129-130

在解决运动学问题中,选择适当的参考系会收到事半功倍之效.  相似文献   

基于心理需求的志愿者激励研究   总被引：2，自引：0，他引：2  

张向群 《科学学研究》2007,25(Z2):414-418

通过对志愿者参与志愿活动的心理需求和动机进行分析,将志愿者按不同的心理需求分为六大类。然后,利用模糊数学的方法建立了不同心理需求志愿者的效用函数,并结合志愿者激励方法和手段的指标体系,分析和探讨了志愿者效用最大化的激励方法。  相似文献   

继承传统文化之精华 发展现代整体衡动观     

唐四喜 《人天科学研究》1996,(2)

初步探讨了元极图的整体衡动观之来源与发展。  相似文献   

科技人员行为偏好的解释框架     

黄敬前 《科学学研究》2006,24(Z1):229-234

本文试图引入经济学的序数效用论,建立分析科技人员科研行为偏好内在规律的理论框架,力图以此揭示多年来高等院校科研院所原创性成果少、科技成果转化状况不佳的内在机理。  相似文献   

元决策与群决策     

李良  尧俞  郭耀煌  何安涛 《软科学》2001,15(5):6-8,16

文章尝试在群决策中引入元决策思想,群决策的两层结构因此而更加清晰。文章还对群决策中元决策的内容,尤其是群效用集结问题进行了讨论。  相似文献