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  • 1
    Electronic Resource
    Electronic Resource
    CYCLIC FATIGUE OF Al2O3 AND Al2O3-Al2TiO5 COMPOSITES IN DIRECT PUSH-PULL (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 20 (1997), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract— A reaction sintering route is developed to produce, “in situ”, composites of alumina-aluminium titanate using alumina and titania as starting powders. Aluminium titanate, can be formed by a solid state reaction between Al2O3 and TiO2 at temperatures above the eutectoid temperature of 1280°C. These composites have different grain sizes of alumina matrix and a different quantity and distribution of aluminium titanate according to the heating cycle used.In the present work direct push-pull tests under cyclic loads have been carried out with both monolithic alumina and alumina-aluminium titanate composites. It has been found that all the samples show a decrease in tensile strength with the number of applied cycles of loading when plotted in graphical form but the slopes of these graphs for both Al2O3-Al2TiO5 composites are lower than for the alumina specimens. The role of aluminium titanate and the alumina matrix grain size in fatigue crack growth resistance has been studied during push-pull tests, where failure occurs by catastrophic propagation of small surface cracks after a very short regime of subcritical crack growth. These results have been compared with measurements of slow stable fatigue crack growth rates in Al2O3-Al2TiO5 composites carried out elsewhere with pre-notched specimens of the compact tension type. These latter tests provide information about the behaviour of significantly long cracks, i.e. cracks that are several millimetres long.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-2695.1997.tb00308.x
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  • 2
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    Perceived Novelty Support and Psychological Needs Satisfaction in Physical Education (2020)
    Molecular Diversity Preservation International
    Details
    Publication Date: 2020-06-11
    Description: In recent years, novelty has been proposed as a potential fourth basic psychological need. In the present study, the behavior of novelty resulting from support from the Physical Education teacher was evaluated in 723 students with an average age of 13.30 years old. The first objective was to validate the Support for Basic Psychological Needs-4 (SBPN-4) in Physical Education questionnaire, which included support for the novelty factor. The second objective was to test the mediation model in order to confirm the effect of support for novelty in relation to basic psychological needs and intrinsic motivation. The results obtained show that the Support for Basic Psychological Needs-4 (SBPN-4) questionnaire is a valid and reliable tool. On the other hand, support for novelty predicts satisfaction of basic psychological needs, particularly novelty satisfaction, which in turn predicts intrinsic motivation. These results show how the students are capable of perceiving the teacher’s support for novelty and how this positively influences their intrinsic motivation. Further investigations are required to continue developing our knowledge of the role of novelty as a basic psychological need.
    Print ISSN: 1661-7827
    Electronic ISSN: 1660-4601
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by Molecular Diversity Preservation International
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  • 3
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    Validation of the Achievement Emotions Questionnaire for Physical Education (AEQ-PE) (2020)
    Molecular Diversity Preservation International
    Details
    Publication Date: 2020-06-24
    Description: The fundamental role of emotions in education has been revealed in recent years. The control-value theory of achievement emotions has been postulated as one of the most used theories in this field. Thanks to the Achievement Emotions Questionnaire (AEQ), achievement emotions have been measured in different subjects and countries. The purpose of this research was to adapt and validate this questionnaire to assess achievement emotions in physical education. The sample of participants consisted of 902 (Mage = 13.15, SD = 1.17) secondary education students from various secondary schools in Spain. The psychometric properties of the Achievement Emotions Questionnaire for Physical Education (AEQ-PE) indicate that the scales are reliable and valid, as demonstrated by exploratory and confirmatory factor analysis, temporal stability, internal consistency and regression analysis. Considering the results achieved in the present study, the AEQ-PE opens a range of possibilities for both teachers and researchers. This instrument will help to understand the role of emotions in student learning and their motivation towards physical education.
    Print ISSN: 1661-7827
    Electronic ISSN: 1660-4601
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by Molecular Diversity Preservation International
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  • 4
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    Effects of Cooperative-Learning Interventions on Physical Education Students’ Intrinsic Motivation: A Systematic Review and Meta-Analysis (2020)
    Molecular Diversity Preservation International
    Details
    Publication Date: 2020-06-21
    Description: The aim was to review the effects of cooperative learning interventions on intrinsic motivation in physical education students, as well as to conduct a meta-analysis to determinate the overall effect size of these interventions. The PRISMA guidelines were followed to conduct this systematic review and meta-analysis. The PEDro Scale was used to assess the risk of bias and the GRADE approach was used to evaluate the quality of the evidence. A total of five studies fulfilled the inclusion criteria and they were included in the meta-analysis. Effect size for intrinsic motivation of each study was calculated using the means and standard deviations of the Perceived Locus of Causality Scale (PLOC) before and after the intervention. The overall effect size for intrinsic motivation was 0.38 (95% CI from 0.17 to 0.60) while the heterogeneity was large. Although four of the five studies reported significant within-group improvements in intrinsic motivation, only three studies showed significant between-group differences in favor of the experimental group. The findings showed that program duration and participant age may be relevant factors that must be considered by educators and researchers to conduct future effective interventions. Cooperative learning interventions could be a useful teaching strategy to improve physical education students’ intrinsic motivation. However, given the large heterogeneity and the low quality of the evidence, these findings must be taken with caution.
    Print ISSN: 1661-7827
    Electronic ISSN: 1660-4601
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by Molecular Diversity Preservation International
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  • 5
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    Decisive Factors for a Greater Performance in the Change of Direction and Its Angulation in Male Basketball Players (2020)
    Molecular Diversity Preservation International
    Details
    Publication Date: 2020-09-10
    Description: A study was made to initially evaluate whether the age category directly could influence anthropometric measurements, functional movement tests, linear sprint (30 m) and strength. Moreover, and as the main purpose, this study aimed to examine the relationship between the time execution and angles in different changes of direction (COD) test with the analyzed sport performance variables. A total sample of 23 basketball players (age: 17.5 ± 2.42 years; height: 184.6 ± 6.68 cm; body weight: 78.09 ± 11.9 kg). Between-groups’ comparison explored the differences between basketball categories (Junior, n = 12; Senior, n = 11). The COD variables were divided by the time execution into low responders (LR) and high responders (HR) to establish comparisons between groups related to COD time execution. Pearson’s correlation coefficient was used to establish correlations between different CODs and sport performance variables. The results showed a greater influence of age category upon COD performance, especially when the cutting angle was sharper (7.05% [Confidence limits (CL) 90%: 2.33; 11.99]; Quantitative chances (QC) 0/2/98), in which athletes need greater application of strength. Moreover, the sharper the angle or the larger the number of cuts made, the greater the relationship with the vertical force–velocity profile (−42.39 [CL 90%: −57.37; −22.16]; QC 100/0/0%). Thus, the usefulness of the f–v profile to implement training programs that optimize the f–v imbalance and the improvement of the COD performance in basketball players is suggested.
    Print ISSN: 1661-7827
    Electronic ISSN: 1660-4601
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by Molecular Diversity Preservation International
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  • 6
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    Perceived Performance, Intrinsic Motivation and Adherence in Athletes (2020)
    Molecular Diversity Preservation International
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    Publication Date: 2020-12-16
    Description: Sports performance depends on a complex interaction of variables, such as psychological, physical, technical and tactical abilities. The purpose of the three studies described in this article was to validate an instrument to measure perceived performance in athletes (studies 1 and 2), and to analyze the predictive power of perceived performance, basic psychological needs and intrinsic motivation on the intention to be physically active (which was used as a predictor of adherence to sport) (study 3). In study 1, the Perceived Performance in Sports Questionnaire was validated in the Spanish sports context, analyzing its factorial structure, reliability, and temporal stability with 146 soccer players. The objective of study 2 was to check the factorial structure of the questionnaire with an objective performance measure (points scored and time played). The sample was 180 young basketball players. The objective of study 3 was to analyze the predictive power of basic psychological needs in exercise, intrinsic motivation, and perceived performance on the intention to be physically active in 339 athletes of fifteen different sports. The results show the reliability and validity of the questionnaire, and positive correlations with the points scored. Finally, the analysis of the structural equation model showed that the satisfaction of the need for competence predicted perceived performance and intrinsic motivation predicted perceived performance and intention to remain physically active.
    Print ISSN: 1661-7827
    Electronic ISSN: 1660-4601
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by Molecular Diversity Preservation International
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