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1.
Panagiotis Symeonidis Alexandros Nanopoulos Apostolos N. Papadopoulos Yannis Manolopoulos 《Information Retrieval》2008,11(1):51-75
Collaborative Filtering (CF) Systems have been studied extensively for more than a decade to confront the “information overload”
problem. Nearest-neighbor CF is based either on similarities between users or between items, to form a neighborhood of users
or items, respectively. Recent research has tried to combine the two aforementioned approaches to improve effectiveness. Traditional
clustering approaches (k-means or hierarchical clustering) has been also used to speed up the recommendation process. In this paper, we use biclustering
to disclose this duality between users and items, by grouping them in both dimensions simultaneously. We propose a novel nearest-biclusters
algorithm, which uses a new similarity measure that achieves partial matching of users’ preferences. We apply nearest-biclusters
in combination with two different types of biclustering algorithms—Bimax and xMotif—for constant and coherent biclustering,
respectively. Extensive performance evaluation results in three real-life data sets are provided, which show that the proposed
method improves substantially the performance of the CF process.
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| Yannis ManolopoulosEmail: |
2.
Piperakis Stylianos M. Sotiriou Apostolos Georgiou Evanthia Thanou Ageliki Zafiropoulou Maria 《Journal of Science Education and Technology》2004,13(1):129-136
The purpose of this study was first to assess and then to improve the diet of Greek primary school children teaching them healthy dietary habits and instructing them to face critically advertisements and media projected dietary models using a program which included intervention on cognitive, emotional, and social level. The results show that our intervention was more effective on the cognitive level and in particular on children's ability to estimate the dietary value of different kinds of food. However, their food preferences were not affected significantly, suggesting that these are more resistant to change since they are already consolidated and, therefore, need longer intervention. 相似文献
3.
Giorgios P Paradisis Athanassios Bissas Panagiotis Pappas Elias Zacharogiannis Apostolos Theodorou Olivier Girard 《Journal of sports sciences》2013,31(17):2026-2036
ABSTRACTAs the effect of performance level on sprinting mechanics has not been fully studied, we examined mechanical differences at maximal running speed (MRS) over a straight-line 35 m sprint amongst sprinters of different performance levels. Fifty male track and field sprinters, divided in Slow, Medium and Fast groups (MRS: 7.67 ± 0.27 m?s?1, 8.44 ± 0.22 m?s?1, and 9.37 ± 0.41 m?s?1, respectively) were tested. A high-speed camera (250 Hz) recorded a full stride in the sagittal plane at 30–35 m. MRS was higher (p < 0.05) in Fast vs. Medium (+11.0%) and Slow (+22.1%) as well as in Medium vs. Slow (+10.0%). Twelve, eight and seven out of 21 variables significantly distinguished Fast from Slow, Fast from Medium and Medium from Slow sprinters, respectively. Propulsive phase was signi?cantly shorter in Fast vs. Medium (?17.5%) and Slow (?29.4%) as well as in Medium vs. Slow (?14.4%). Fast sprinters had significantly higher vertical and leg stiffness values than Medium (+44.1% and +18.1%, respectively) and Slow (+25.4% and +22.0%, respectively). MRS at 30–35 m increased with performance level during a 35-m sprint and was achieved through shorter contact time, longer step length, faster step rate, and higher vertical and leg stiffness. 相似文献
4.
This study examined the role of teachers’ personal characteristics and mental health status on their frequency ratings of student problem behaviour. A sample of 121 primary school teachers were asked to rate the frequency of a student’s behavioural problems, and to self-report their personality traits, psychopathology symptoms and burnout. Overall, the results revealed that teachers’ ratings were significantly predicted by their psychopathology symptoms and to a lesser extent by their personality traits and burnout levels. Student and teacher demographic characteristics were also predictive of teacher ratings. Since teachers are among the primary informants of students’ mental health, the results of this study pose the need to take into consideration teachers’ individual characteristics, when their ratings are critically evaluated during a student’s referral process. 相似文献
5.
Kostas Dimopoulos Apostolos Asimakopoulos 《Journal of Science Education and Technology》2010,19(3):246-265
This study aims to explore navigation patterns and preferred pages’ characteristics of ten secondary school students’ searching the web for information about cloning. The students navigated the Web for as long as they wished in a context of minimum support of teaching staff. Their navigation patterns were analyzed using audit trail data software. The characteristics of their preferred Web pages were also analyzed using a scheme of analysis largely based on socio-linguistics and socio-semiotics approaches. Two distinct groups of students could be discerned. The first consisted of more competent students, who during their navigation visited fewer relevant pages, however of higher credibility and more specialized content. The second group consists of weaker students, who visited more pages, mainly of lower credibility and rather popularized content. Implications for designing educational web pages and teaching are discussed. 相似文献
6.
Seismic behavior of diaphragm-through connections of concrete-filled square steel tubular columns and H-shaped steel beams 总被引：1，自引：1，他引：0
Based on the introductions of a type of diaphragm-through connection between concrete-filled square steel tubular columns (CFSSTCs) and H-shaped steel beams,a finite element model of the connection is developed and used to investigate the seismic behavior of the connection.The results of the finite element model are validated by a set of cyclic loading tests.The cyclic loading tests and the finite element analyses indicate that the failure mode of the suggested connections is plastic hinge at the beam with inelastic rotation angle exceeding 0.04 rad.The suggested connections have sufficient strength,plastic deformation and energy dissipation capacity to be used in composite moment frames as beam-to-column rigid connections. 相似文献
7.
Tassos A. Mikropoulos Anthimos Chalkidis Apostolos Katsikis Anastassios Emvalotis 《Education and Information Technologies》1998,3(2):137-148
This case study reports on an investigation of the attitude of education students towards virtual reality (VR) as a tool in the educational process, and towards virtual learning environments on specific disciplines. Our results indicate a favourable attitude towards VR in the educational process. Although immersion was not supported in this study, half of the students declared immersion experiences. Students consider the mouse the most effective input device for navigation in virtual environments, with a joystick the second one. Because the sampling population is small, the qualitative results must be regarded as tentative. There is, however, a need for further investigation, which is currently being undertaken by our group. 相似文献
8.
Apostolos S. Theodorou Vassilios Panoutsakopoulos Timothy A. Exell Polyxeni Argeitaki Giorgos P. Paradisis Athanasia Smirniotou 《Journal of sports sciences》2017,35(4):346-354
The aim of this study was to investigate the relative influence of step length (SL) and step frequency (SF) on step velocity (SV) during the approach run of high-level long jumpers and to quantify the asymmetry of these step characteristics. Spatiotemporal data of the approach run were collected during national competition from 10 long jumpers (age 26.2 ± 4.1 years, height 1.84 ± 0.06 m, mass 72.77 ± 3.23 kg, personal best performance 7.96 ± 0.30 m). Analyses were conducted for total approach, early approach and late approach. For the total approach 4/10 athletes were SF reliant and 6/10 athletes favoured neither characteristic. At the early approach, 3/10 athletes were SF reliant and 7/10 athletes favoured neither. During late approach 2/10 athletes demonstrated SL reliance, 7/10 athletes were SF reliant and 1/10 athletes favoured neither. Four athletes displayed significant asymmetry for SL and three for SF. However, no athletes demonstrated significant asymmetry for SV indicating that the asymmetrical demands of take-off do not have a marked influence on step characteristic asymmetry, probably due to the constraints of the event. Consideration should be given to the potentially conflicting demands between limbs for individual athletes. 相似文献
9.
Tassos Mikropoulos Anthimos Chalkidis Apostolos Katsikis Photini Kossivaki 《Education and Information Technologies》1997,2(2):131-142
This article proposes the use of virtual realities (VR) in environmental education. It also presents the first results of an application to the phenomenon of eutrophication in lakes. Although our virtual environments are not immersive, they give the opportunity to students and educators to develop their own worlds and understand the population dynamics in a lake. The learning environment can be manipulated and controlled in a powerful way, enhancing students experiences leading to knowledge construction, and sensitizing students to current environmental problems. Our pedagogical approach is to build a theoretical model for virtual learning environments, expanding constructivism and combining it with experiential learning. Our operational and practical approach is to exploit the characteristics of desktop VR systems in virtual learning environments 相似文献
10.
Based on the characteristics of an L-shaped column composed of concrete-filled square steel tubes, the axial compression experiment and nonlinear finite element analysis were carried out to study the mechanical property of the L-shaped column. The load-displacement curve for the L-shaped column, the deflection and load-strain curves for the mono columns were obtained by the axial compression experiment. The results show that the L-shaped column exhibits a flexural-torsional buckling failure mode. The numerical simulation by the finite element analysis shows that the bearing capacity and failure mode are in accordance with those of the axial compression experiment and the feasi- bility of the finite element analysis is proved. For the calculation of the bearing capacity of the L-shaped column com- posed of concrete-filled square steel tubes, an analytical method is proposed based on the theory of the elastic stability and spatial truss model. The results of the analytical method are in good agreement with those of the axial compression experiment and the finite element analysis. 相似文献