Relevance-based language modelling for recommender systems     

Javier Parapar  Alejandro Bellogín  Pablo Castells  Álvaro Barreiro 《Information processing & management》2013

Relevance-Based Language Models, commonly known as Relevance Models, are successful approaches to explicitly introduce the concept of relevance in the statistical Language Modelling framework of Information Retrieval. These models achieve state-of-the-art retrieval performance in the pseudo relevance feedback task. On the other hand, the field of recommender systems is a fertile research area where users are provided with personalised recommendations in several applications. In this paper, we propose an adaptation of the Relevance Modelling framework to effectively suggest recommendations to a user. We also propose a probabilistic clustering technique to perform the neighbour selection process as a way to achieve a better approximation of the set of relevant items in the pseudo relevance feedback process. These techniques, although well known in the Information Retrieval field, have not been applied yet to recommender systems, and, as the empirical evaluation results show, both proposals outperform individually several baseline methods. Furthermore, by combining both approaches even larger effectiveness improvements are achieved.  相似文献   

Anthropometric,physiological and maturational characteristics in selected elite and non-elite male adolescent basketball players     

Jon Torres-Unda  Idoia Zarrazquin  Javier Gil  Fátima Ruiz  Amaia Irazusta  Maider Kortajarena 《Journal of sports sciences》2013,31(2):196-203

Abstract

We investigated the anthropometric, physiological and maturation characteristics of young players (13–14 years old) associated with being successful in basketball. Body parameters were measured (stature, total body mass, skinfolds and lengths) and physiological capacities were assessed by endurance, sprint (20 m), jump and dribbling tests. Chronological age (CA) was recorded and maturity estimated using predicted age at peak height velocity (APHV). Anthropometric analysis indicated that elite players were taller, heavier and had a higher percentage of muscle. Further, physiological testing showed that these elite players perform better in jump, endurance, speed and agility tests (especially in the agility and ball tests). In addition, these skills are correlated with point average during the regular season. More basketball players born in the first semester of the year are selected and there is a predominance of early-maturing boys among those selected for the elite team. Those who are more mature have advantages in anthropometric characteristics and physiological test results. In conclusion, around puberty, physical and physiological parameters associated with maturity and CA are important in determining the success of basketball players. These findings should be taken into account by trainers and coaches, to avoid artificial bias in their selection choices.  相似文献   

Comparative analysis of sequentiality using SDIS-GSEQ and THEME: A concrete example in soccer     

Daniel Lapresa  Javier Arana  M. Teresa Anguera  Belén Garzón 《Journal of sports sciences》2013,31(15):1687-1695

Abstract

Within an observational design aimed at studying what type of soccer is better adapted to the possibilities of the 11–12 year-old child, a comparison was made of the results obtained using two fully consolidated analysis techniques in observational methods, and which form the basis in the development of two respective software programs: SDIS-GSEQ and THEME, which allow one to detect the existence of sequential patterns hidden in a data set. This work is intended to shed light on the comparison of results obtained using these two analysis techniques. In particular, the data used for the analysis are multicode event data (using the lexicon of the sequential analysis), and do not incorporate the duration parameter. Accordingly, for the detection of regular structures using the THEME program (T-patterns), a constant duration has conventionally been assigned to each occurrence. Using THEME, among the greatest number of sequential structures detected, diachronic and synchronic correspondence was observed (T-patterns reflecting identical multi-events) with each and every one of the sequential patterns obtained using the lag technique, by the SDIS-GSEQ software. This coincidence strengthens the link between the algorithms that support SDIS-GSEQ and THEME. The results indicate that 7-a-side soccer and 9-a-side soccer types facilitate the spatial mastery of the game by the child, compared with the adult form, 11-a-side soccer.  相似文献   

Observational analysis of the offensive sequences that ended in a shot by the winning team of the 2010 UEFA Futsal Championship     

Daniel Lapresa  Leandro Álvarez  Javier Arana  Belén Garzón  Valvanera Caballero 《Journal of sports sciences》2013,31(15):1731-1739

Abstract

This article analyses the offensive phase of the national team than won the 2010 UEFA Championship. More specifically, the observational sampling includes all plays in which the Spanish national futsal team managed to “shoot” in the competition in question. This data was obtained by adapting an observational and recording tool typically used for football to the technical specifications of futsal; the SOF-CODER (Jonsson et al., 2006). Two types of analysis have been performed. One statistical analysis using the SPSS programme, version 15.0, the most relevant results from which refer to the significant differences found on linking: the zone from which the shot is made and the type of shot (χ² = 55.821, P = 0.006); and the contact surface used and the type of shot (χ² = 30.293, P = 0.017). And another, using the Theme programme, version 5.0, through which regular behaviour structures (temporal patterns) have been detected within the plays that include shooting. The temporal patterns obtained – in addition to elaborating on the relationship between the area from which the shot is made, the contact surface used and the type of shot – enable a tactical interpretation of the technical actions that support the development of the offensive phase of futsal.  相似文献   

Effects of plyometric jump training on the physical fitness of young male soccer players: Modulation of response by inter-set recovery interval and maturation status     

Rodrigo Ramirez-Campillo  Cristian Alvarez  Javier Sanchez-Sanchez  Maamer Slimani  Paulo Gentil  Mohamed Souhaiel Chelly 《Journal of sports sciences》2013,31(23):2645-2652

ABSTRACT

The effects of plyometric jump training on the physical fitness of male youth (age = 10–17 years) soccer players was examined in relation to inter-set recovery intervals and the maturity of the players in a single-blind, randomized-and controlled crossover trial. Jumping tests and kicking velocities were measured before (T₀), after a 6 week control period (T₁), after 6 weeks of plyometrics (T₂), after 6 weeks of wash-out (T₃), and after a further 6 weeks of plyometrics (T₄). Subjects were divided into pre- and post- peak-height-velocity (PHV) groups, and were randomly assigned to 30 s or 120 s inter-set intervals during periods T₂ and T₄. Any changes in jumping and maximum kicking velocities during T₁ and T_3, had trivial effect sizes (0.01–0.15), but small to moderate improvements (effect size = 0.20–0.99) were observed in both groups during T₂ and T₄. Gains in pre-PHV players were similar for the two inter-set intervals, but gains in post-PHV players were greater (p < 0.05) with an inter-set recovery of 120 s than with a 30 s recovery. We conclude that plyometric jump training improves the physical fitness of adolescents, irrespective of their maturity, but that in older individuals gains are greater with a longer inter-set recovery interval.  相似文献   

Degradability of building stone: Influence of the porous network on the rate of dissolution of carbonate and evaporitic rocks     

Víctor Cárdenes Van den Eynde  Felix Javier Mateos  Remigio Paradelo 《Journal of Cultural Heritage》2013,14(2):89-96

The susceptibility to weathering of eleven carbonate and evaporitic Spanish building rocks was studied by means of dissolution experiments. Mineralogy, petrology, geochemistry and porosity of the rocks were also characterized in order to determine the potential relationships between these properties of the rocks and their dissolution rates. Rock slabs were submerged in a 0.1 M HCl acid solution for 72 h and the amounts of Ca, Mg and S released were measured, as well as the weight loss of the samples during the acid attack. Alabasters, which presented very low porosity, were dissolved to a lesser extent than limestones and dolostones in the time of the experiment. A significant positive correlation was found for connected with the weight loss of the rocks during dissolution and with the kinetic rate of Ca dissolution. Overall, the results highlight the influence of the porous network in the degradability of building stones by controlling their rate of dissolution. There is a positive correlation for all the rocks between weight loss along acidic attack and connected porosity, but no relationship between mineralogical and petrographical composition and susceptibility to dissolution.  相似文献   

Corrigendum to “The measurement of low- and high-impact in citation distributions: Technical results” [J. Informetrics 5 (2011) 48–63]     

Pedro Albarrán  Ignacio Ortũno  Javier Ruiz-Castillo 《Journal of Informetrics》2012,6(4):515

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Modelling the success of learning management systems: application of latent class segmentation using FIMIX-PLS     

Jorge Arenas-Gaitán  Francisco Javier Rondán-Cataluña  Patricio E. Ramírez-Correa 《Interactive Learning Environments》2018,26(1):135-147

There is not a unique attitude towards the implementation of digital technology in educational sceneries. This paper aims to validate an adaptation of the DeLone and McLean information systems success model in the context of a learning management system. Furthermore, this study means to prove (1) the necessity of segmenting students in order to fit the model more accurately and (2) the impact of other new Internet tools on students’ perceptions with regard to learning management systems. Partial least squares has been used to analyse the measurement and the structural model. Subsequently, the Finite Mixture Partial Least Squarestechnique has been employed to examine unobserved heterogeneity and to find users’ segments. The results of this research indicate that to segment between two groups of students is especially useful in order to improve the understanding of the success of a learning management system. This segmentation is made according to the importance which the students attribute to the new Internet tools to support their learning.  相似文献   

Effects of structural components of artificial turf on the transmission of impacts in football players     

Alberto Encarnación-Martínez  Antonio García-Gallart  Ana M. Gallardo  Juan A. Sánchez-Sáez.  Javier Sánchez-Sánchez 《Sports biomechanics / International Society of Biomechanics in Sports》2018,17(2):251-260

The third generation of artificial turf systems (ATS) has matched the mechanical behaviour of natural grass, but today a high heterogeneity at structural level and mechanical behaviour in the new ATS also exists. The objective was to analyse the effect of the structural components of ATS football pitches and running speed on the capacity of impact attenuation. A total of 12 athletes were evaluated at three speed conditions (3.33 m/s, 4 m/s and maximum speed) on four different ATS, classifying them by their components (length of fibre, type of in-fill and sub-base). Impact attenuation was significantly higher in ATS3, characterised by longer fibre compared to other ATS with less fibre length. The ATS4 with a higher length fibre and built on compacted granular material proportioned significantly lower values in the maximum peaks of tibia acceleration. Finally, as speed increases, the peak tibia impacts were significantly higher. Longer fibre length and the capacity to accommodate a higher quantity of infill facilitate higher impact attenuation. Equally, a compacted granular sub-base is related to lower magnitude of maximum tibia peaks. Finally, the magnitude of the tibia acceleration peaks is dependent of running speed for all ATS analysed, being higher as speed increases.  相似文献   

Mixed order robust adaptive control for general linear time invariant systems     

Javier A. Gallegos  Manuel A. Duarte-Mermoud  Rafael Castro-Linares 《Journal of The Franklin Institute》2018,355(8):3399-3422

We provide a solution to the adaptive control problem of an unknown linear system of a given derivation order, using a reference model or desired poles defined in a possibly different derivation order and employing continuous adjustment of parameters ruled by possibly another different derivation order. To this purpose, we present an extension for the fractional settings of the Bezout’s lemma and gradient steepest descent adjustment. We analyze both the direct and indirect approaches to adaptive control. We discuss some robustness advantages/disadvantages of the fractional adjustment of parameters in comparison with the integer one and, through simulations, the possibility to define optimal derivation order controllers.  相似文献