Scale and Translation Invariant Collaborative Filtering Systems   总被引：1，自引：0，他引：1  

Daniel Lemire 《Information Retrieval》2005,8(1):129-150

Collaborative filtering systems are prediction algorithms over sparse data sets of user preferences. We modify a wide range of state-of-the-art collaborative filtering systems to make them scale and translation invariant and generally improve their accuracy without increasing their computational cost. Using the EachMovie and the Jester data sets, we show that learning-free constant time scale and translation invariant schemes outperforms other learning-free constant time schemes by at least 3% and perform as well as expensive memory-based schemes (within 4%). Over the Jester data set, we show that a scale and translation invariant Eigentaste algorithm outperforms Eigentaste 2.0 by 20%. These results suggest that scale and translation invariance is a desirable property.  相似文献   

Screening for risk of low energy availability in athletic and recreationally active females in Ireland     

Danielle M. Logue  Sharon M. Madigan  Mirjam Heinen  Sarah-Jane McDonnell  Eamonn Delahunt  Clare A. Corish 《European Journal of Sport Science》2019,19(1):112-122

ABSTRACT

Introduction: Low energy availability (LEA) results in physiological adaptations, which can contribute to unfavourable health outcomes. Little information exists on risk of LEA in active individuals competing in different sports or levels of competition. The aims of this study were to (1) identify risk of LEA in females competing at different levels of competition and (2) investigate associations between risk of LEA, illness and dietary habits. Methods: The validated questionnaire, ‘Low Energy Availability in Females Questionnaire’ was distributed online (November 2016–February 2017) to assess risk of LEA. Twenty-nine additional questions collected information on demographics, illness history and dietary habits. Participants were considered at risk of LEA if they attained a score of?≥?8 and were grouped into: (i) international; (ii) provincial/inter-county; (iii) competitive; and (iv) recreationally active. Chi-square and logistic regression analyses were used to explore differences between those at risk or not at risk of LEA. Results: Risk of LEA was identified in 40% (n?=?331) of 833 participants and was 1.7 and 1.8 times more likely in international and provincial/inter-county athletes compared to those who were recreationally active (International: odds ratios (OR) 1.68, 95% confidence intervals (95%CI) 1.12–2.54; Provincial/inter-county: OR 1.83, 95%CI 1.20–2.77). In participants at risk of LEA, missing >22 days of training during the previous year due to illness occurred 3 times more frequently (OR 3.01, 95%CI 1.81–5.02). Conclusion: Risk of LEA was widespread in this heterogeneous sample. Awareness of LEA and the development of appropriate energy management strategies to ensure athlete health across levels of competition are required.  相似文献   

中印两国勘探开发境外能源战略比较研究     

张魁中 《株洲师范高等专科学校学报》2007,12(6):18-21

由于中国和印度都面对着同样的国际环境,且基本国情相似,特别是在能源安全方面都面临着相同或相似的问题,即近年来经济呈现高速和持续增长,能源问题,尤其是石油问题已成为制约中印经济发展的最大瓶颈,中印都积极面向全球部署本国的能源战略,为迅猛增长的经济谋求充足的能源保障。我国的能源战略应向石油进口渠道多样化及多方面与石油输出国乃至消费国加强合作的途径发展。  相似文献   

P-V图与热力学第一定律中的诸量     

柴英  王少华 《陕西理工学院学报(社会科学版)》1996,(6)

通过讨论热力学系统在准静态过程ΔE、A、Q诸量与P－V图中过程曲线之间的关系，可直接从P—V图上判断内能的增减、做功正负及热量交换的方向。  相似文献   

ZnO半导体光催化处理含酚废水的研究     

康慧敏  康锡惠 《天津大学学报(英文版)》1996,(2)

利用中压汞灯作光源，ＺｎＯ为催化剂，研究了辐射波长、ＺｎＯ－酚悬浮液组成和搅拌方式等因素对酚分解率的影响．ＺｎＯ半导体光催化分解酚的适宜条件为：辐射波长３６０～４２０ｎｍ，ＺｎＯ－酚悬浮液的含酚量＜２００ｍｇ／ｌ，ＺｎＯ浓度３～８ｇ／ｌ，ｐＨ＝５～７，反应温度２５℃～４０℃，空气搅拌．酚的分解机理可能涉及酚与光生空穴反应和酚与辐照过程中产生的·ＯＨ自由基反应两条途径  相似文献   

关于变频调速的应用与节能分析   总被引：1，自引：0，他引：1  

吴文斌  孙开福 《鸡西大学学报》2006,6(6):70-71

文章通过分析变频器调速的节能原理,并结合一个热电厂的变频器改造后的实例,阐述了变频调速的节能效果,提高了设备运行可靠性和节能降耗性。  相似文献   

细胞膜Na+-K+主动输运过程的热力学分析     

刘贵忠  刘树坤 《德州学院学报》2002,18(4):19-21

研究分析了Na^ -K^ 在跨膜主动输运过程中，细胞能量(由ATP分解提供)在各阶段的耗散情况．并且把ATP酶视为一个子系统，探讨了其在一个循环中发生的生物物理过程的规律性，对于深入了解细胞生命活动的内在机制提供了一种有益的研究方法。  相似文献   

质点组内力的功改变质心动能的条件     

田志川 《通化师范学院学报》2003,24(6):25-26

讨论了质点组内力的功是可以改变质心动能的，以及所满足的条件．  相似文献   

青少年体力活动干预新方式——体感游戏对青少年身体活动的影响分析     

袁川 《湖北体育科技》2016,(9):784-787

体感游戏作为体育运动与电子科技的结合产品,对其在青少年体力活动干预方面的研究有重要意义。研究从体力活动的促进、能量消耗、运动康复、社会价值以及心理效应等方面对体感游戏进行分析,发现体感游戏对青少年体力活动有明显促进作用,能满足其锻炼的需求,且对青少年心理健康具有积极地影响,能作为青少年体力活动干预的有效手段之一。  相似文献   

Structural dynamic responses analysis applying differential quadrature method     

PU Jun-ping ZHENG Jian-jun 《浙江大学学报(A卷英文版)》2006,7(11):1831-1838

INTRODUCTION The differential quadrature method (DQM) was proposed by Bellman and Casti as an analogous ex- tension of the quadrature method for integrals (Bellman and Casti, 1971; Bellman et al., 1972). It can be essentially expressed as the values of the de- rivatives at each grid point as weighted linear sums approximately of the function values at all grid points within the domain under consideration. As a distinct numerical solution technique to obtain the initial and/or boundary …  相似文献