动态雾计算网络中基于在线学习的任务卸载算法     

谭友钰  陈蕾  周明拓  王昆仑  杨旸  张武雄 《中国科学院大学学报》2020,37(5):688-698

任务卸载是雾计算的主要技术之一，即计算能力不足的节点将任务卸载给具有富余资源的节点帮助计算。以优化任务平均卸载时延和提升卸载服务成功率为目标，利用多臂老虎机理论为动态雾计算网络提出一种基于在线学习的任务卸载算法，可实时做出最优卸载决策。将该算法扩展到非稳定网络状态，使之可以动态追踪网络中节点的资源与环境变化，实时调整卸载决策。详细分析所提出算法的性能、复杂度和存储占用情况。仿真结果表明，这两种算法可达到的长期平均任务卸载时延均十分接近理想算法下的最优时延，卸载服务成功率也得到显著提升。此外，所提算法在非稳定的网络状态下能够追踪到计算资源与环境的变化。  相似文献   

Motivation counteracts fatigue-induced performance decrements in soccer passing performance     

Jeroen C.M. Barte  Arne Nieuwenhuys  Sabine A.E. Geurts  Michiel A.J. Kompier 《Journal of sports sciences》2019,37(10):1189-1196

Recent theories suggest that negative effects of fatigue on performance are determined by perception of effort and motivation rather than being directly caused by reaching physiological limits. In the current experiment, the influence of motivation on fatigue-induced decrements in soccer performance was experimentally investigated. Sixty amateur soccer players performed a validated soccer-passing test before and after a fatigue protocol. Results showed that players’ motivation and performance decreased after the fatigue protocol for players in the control group. In contrast, players in the motivation group (i.e., with motivation experimentally induced after the fatigue protocol) were able to uphold their motivation and increase their performance. These results indicate that motivation plays a crucial role in performance under fatigue, as fatigue-induced decrements in soccer passing performance can be counteracted by high levels of motivation. Future research may explore the limits of this counteracting effect and extend findings to other relevant performance aspects.  相似文献   

非稳态雾赋能网络中的在线任务卸载方法     

朱兆伟  刘婷  钱骅  罗喜良 《中国科学院大学学报》2020,37(5):699-707

为充分发掘分布在不同位置上的雾节点的计算资源，任务卸载被寄予众望。在雾计算场景下，以尽可能减少任务卸载的长期成本为目标，试图寻找一个高效的在线任务卸载方法。为此，这一问题被建模成一个随机规划问题，该问题中系统参数所对应的随机变量的期望会在未知时刻突变，系统参数相关信息只能在任务完成后的反馈中获得。基于非稳态多臂老虎机模型，提出一个高效的算法来解决这一具有挑战性的随机优化问题，给出理论分析证明该算法的渐进最优性。数值实验证明了该算法的优越性。  相似文献   

Information retrieval in the workplace: A comparison of professional search practices     

Tony Russell-Rose  Jon Chamberlain  Leif Azzopardi 《Information processing & management》2018,54(6):1042-1057

Legal researchers, recruitment professionals, healthcare information professionals, and patent analysts all undertake work tasks where search forms a core part of their duties. In these instances, the search task is often complex and time-consuming and requires specialist expertise to identify relevant documents and insights within large domain-specific repositories and collections. Several studies have been made investigating the search practices of professionals such as these, but few have attempted to directly compare their professional practices and so it remains unclear to what extent insights and approaches from one domain can be applied to another. In this paper we describe the results of a survey of a purposive sample of 108 legal researchers, 64 recruitment professionals and 107 healthcare information professionals. Their responses are compared with results from a previous survey of 81 patent analysts. The survey investigated their search practices and preferences, the types of functionality they value, and their requirements for future information retrieval systems. The results reveal that these professions share many fundamental needs and face similar challenges. In particular a continuing preference to formulate queries as Boolean expressions, the need to manage, organise and re-use search strategies and results and an ambivalence toward the use of relevance ranking. The results stress the importance of recall and coverage for the healthcare and patent professionals, while precision and recency were more important to the legal and recruitment professionals. The results also highlight the need to ensure that search systems give confidence to the professional searcher and so trust, explainability and accountability remains a significant challenge when developing such systems. The findings suggest that translational research between the different areas could benefit professionals across domains.  相似文献   

A study of results overlap and uniqueness among major Web search engines     

Amanda Spink  Bernard J. Jansen  Chris Blakely  Sherry Koshman 《Information processing & management》2006

The performance and capabilities of Web search engines is an important and significant area of research. Millions of people world wide use Web search engines very day. This paper reports the results of a major study examining the overlap among results retrieved by multiple Web search engines for a large set of more than 10,000 queries. Previous smaller studies have discussed a lack of overlap in results returned by Web search engines for the same queries. The goal of the current study was to conduct a large-scale study to measure the overlap of search results on the first result page (both non-sponsored and sponsored) across the four most popular Web search engines, at specific points in time using a large number of queries. The Web search engines included in the study were MSN Search, Google, Yahoo! and Ask Jeeves. Our study then compares these results with the first page results retrieved for the same queries by the metasearch engine Dogpile.com. Two sets of randomly selected user-entered queries, one set was 10,316 queries and the other 12,570 queries, from Infospace’s Dogpile.com search engine (the first set was from Dogpile, the second was from across the Infospace Network of search properties were submitted to the four single Web search engines). Findings show that the percent of total results unique to only one of the four Web search engines was 84.9%, shared by two of the three Web search engines was 11.4%, shared by three of the Web search engines was 2.6%, and shared by all four Web search engines was 1.1%. This small degree of overlap shows the significant difference in the way major Web search engines retrieve and rank results in response to given queries. Results point to the value of metasearch engines in Web retrieval to overcome the biases of individual search engines.  相似文献   

四种搜索引擎的比较研究   总被引：12，自引：0，他引：12  

陈继红  青晓 《情报科学》2003,21(10):1084-1087

本文对目前常用的4种中文搜索引擎：Google、百度、天网、Openfind的索引数据库收录范围、检索功能、检索结果显示格式、用户界面等方面进行了比较分析，并指出它们各自的优势与不足。  相似文献   

基于数据可重用的运动估计低功耗VLSI实现     

伊蔚  金文光  沈建民  周斌 《科技通报》2006,22(6):855-859

块匹配全局搜索算法(FSBM)是效果最好的运动估计算法,但是由于它庞大的运算量限制了它的应用,特别是在数字多媒体终端等对实时性和功耗要求比较高的应用场合。针对这种情况,作者提出的处理结构结合了数据重用和低功耗技术,使得该结构的功耗比传统的全局搜索结构降低50%的功耗,数据可重用性大为提高,确保了每个数据只需被读取一次,这样就确保了较少的I/O端口数和片上内存,同时实现100%的硬件资源利用率。  相似文献   

网络计量学   总被引：19，自引：0，他引：19  

徐久龄  许莲莲 《情报科学》2002,20(1):62-65

本文回顾了计量学的产生和发展的历程，指出在网络环境下网络计量学产生的必然性。并着重探讨了网络计量学的主要特征、研究方法、研究对象范围和在网络环境中的应用。  相似文献   

Comparing rankings of search results on the Web   总被引：1，自引：0，他引：1  

Judit Bar-Ilan   《Information processing & management》2005,41(6):1511-1519

The Web has become an information source for professional data gathering. Because of the vast amounts of information on almost all topics, one cannot systematically go over the whole set of results, and therefore must rely on the ordering of the results by the search engine. It is well known that search engines on the Web have low overlap in terms of coverage. In this study we measure how similar are the rankings of search engines on the overlapping results.We compare rankings of results for identical queries retrieved from several search engines. The method is based only on the set of URLs that appear in the answer sets of the engines being compared. For comparing the similarity of rankings of two search engines, the Spearman correlation coefficient is computed. When comparing more than two sets Kendall’s W is used. These are well-known measures and the statistical significance of the results can be computed. The methods are demonstrated on a set of 15 queries that were submitted to four large Web search engines. The findings indicate that the large public search engines on the Web employ considerably different ranking algorithms.  相似文献   

组织支持认知与领导—成员交换对员工回报的影响实证研究   总被引：3，自引：0，他引：3  

吴继红 《软科学》2006,20(5):63-66

根据组织支持认知(Perce ived O rgan izational Support)和领导—成员交换(LeaderM ember Exchange)的研究,员工既与组织也与主管建立了社会交换关系。在借鉴国内外的相关理论的基础上,通过100对主管和员工的问卷调查验证了企业员工的组织支持认知对他们的任务绩效、组织公民行为和组织承诺有正向的影响;而企业员工的领导—成员交换认知对他们的组织公民行为有正向的影响。  相似文献